e1000e: Avoid hw_error if legacy mode used

https://bugzilla.redhat.com/show_bug.cgi?id=1787142
The emulation issues hw_error if PSRCTL register
is written, for example, with zero value.
Such configuration does not present any problem when
DTYP bits of RCTL register define legacy format of
transfer descriptors. Current commit discards check
for BSIZE0 and BSIZE1 when legacy mode used.

Acked-by: Dmitry Fleytman <dmitry.fleytman@gmail.com>
Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/e1000e_core.c

@@ -2813,12 +2813,15 @@ e1000e_set_eitr(E1000ECore *core, int index, uint32_t val)
 static void
 e1000e_set_psrctl(E1000ECore *core, int index, uint32_t val)
 {
-    if ((val & E1000_PSRCTL_BSIZE0_MASK) == 0) {
-        hw_error("e1000e: PSRCTL.BSIZE0 cannot be zero");
-    }
+    if (core->mac[RCTL] & E1000_RCTL_DTYP_MASK) {
+
+        if ((val & E1000_PSRCTL_BSIZE0_MASK) == 0) {
+            hw_error("e1000e: PSRCTL.BSIZE0 cannot be zero");
+        }
 
-    if ((val & E1000_PSRCTL_BSIZE1_MASK) == 0) {
-        hw_error("e1000e: PSRCTL.BSIZE1 cannot be zero");
+        if ((val & E1000_PSRCTL_BSIZE1_MASK) == 0) {
+            hw_error("e1000e: PSRCTL.BSIZE1 cannot be zero");
+        }
     }
 
     core->mac[PSRCTL] = val;