net: Drop unusual use of do { } while (0);

For a couple of macros in pcnet.c, we have to provide a new scope
to avoid compiler warnings about declarations in the middle of a
switch statement that aren't in a sub-scope.  But use of
'do { ... } while (0);' merely to provide that new scope is arcane
overkill, compared to just using '{ ... }'.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20171201232433.25193-2-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/net/pcnet.c

@@ -456,32 +456,32 @@ static inline void pcnet_rmd_store(PCNetState *s, struct pcnet_RMD *rmd,
 #define CHECK_RMD(ADDR,RES) do {                \
     switch (BCR_SWSTYLE(s)) {                   \
     case 0x00:                                  \
-        do {                                    \
+        {                                       \
             uint16_t rda[4];                    \
             s->phys_mem_read(s->dma_opaque, (ADDR), \
                 (void *)&rda[0], sizeof(rda), 0); \
             (RES) |= (rda[2] & 0xf000)!=0xf000; \
             (RES) |= (rda[3] & 0xf000)!=0x0000; \
-        } while (0);                            \
+        }                                       \
         break;                                  \
     case 0x01:                                  \
     case 0x02:                                  \
-        do {                                    \
+        {                                       \
             uint32_t rda[4];                    \
             s->phys_mem_read(s->dma_opaque, (ADDR), \
                 (void *)&rda[0], sizeof(rda), 0); \
             (RES) |= (rda[1] & 0x0000f000L)!=0x0000f000L; \
             (RES) |= (rda[2] & 0x0000f000L)!=0x00000000L; \
-        } while (0);                            \
+        }                                       \
         break;                                  \
     case 0x03:                                  \
-        do {                                    \
+        {                                       \
             uint32_t rda[4];                    \
             s->phys_mem_read(s->dma_opaque, (ADDR), \
                 (void *)&rda[0], sizeof(rda), 0); \
             (RES) |= (rda[0] & 0x0000f000L)!=0x00000000L; \
             (RES) |= (rda[1] & 0x0000f000L)!=0x0000f000L; \
-        } while (0);                            \
+        }                                       \
         break;                                  \
     }                                           \
 } while (0)
@@ -489,22 +489,22 @@ static inline void pcnet_rmd_store(PCNetState *s, struct pcnet_RMD *rmd,
 #define CHECK_TMD(ADDR,RES) do {                \
     switch (BCR_SWSTYLE(s)) {                   \
     case 0x00:                                  \
-        do {                                    \
+        {                                       \
             uint16_t xda[4];                    \
             s->phys_mem_read(s->dma_opaque, (ADDR), \
                 (void *)&xda[0], sizeof(xda), 0); \
             (RES) |= (xda[2] & 0xf000)!=0xf000; \
-        } while (0);                            \
+        }                                       \
         break;                                  \
     case 0x01:                                  \
     case 0x02:                                  \
     case 0x03:                                  \
-        do {                                    \
+        {                                       \
             uint32_t xda[4];                    \
             s->phys_mem_read(s->dma_opaque, (ADDR), \
                 (void *)&xda[0], sizeof(xda), 0); \
             (RES) |= (xda[1] & 0x0000f000L)!=0x0000f000L; \
-        } while (0);                            \
+        }                                       \
         break;                                  \
     }                                           \
 } while (0)