hw/net/e1000: Move macreg[] arrays to .rodata to save 1MiB of .data

Each array consumes 256KiB of .data. As we do not reassign entries,
we can move it to the .rodata section, and save a total of 1MiB of
.data (size reported on x86_64 host).

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Dmitry Fleytman <dmitry.fleytman@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20200305010446.17029-3-philmd@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/net/e1000.c

@@ -1151,7 +1151,7 @@ set_ims(E1000State *s, int index, uint32_t val)
 
 #define getreg(x)    [x] = mac_readreg
 typedef uint32_t (*readops)(E1000State *, int);
-static readops macreg_readops[] = {
+static const readops macreg_readops[] = {
     getreg(PBA),      getreg(RCTL),     getreg(TDH),      getreg(TXDCTL),
     getreg(WUFC),     getreg(TDT),      getreg(CTRL),     getreg(LEDCTL),
     getreg(MANC),     getreg(MDIC),     getreg(SWSM),     getreg(STATUS),
@@ -1207,7 +1207,7 @@ enum { NREADOPS = ARRAY_SIZE(macreg_readops) };
 
 #define putreg(x)    [x] = mac_writereg
 typedef void (*writeops)(E1000State *, int, uint32_t);
-static writeops macreg_writeops[] = {
+static const writeops macreg_writeops[] = {
     putreg(PBA),      putreg(EERD),     putreg(SWSM),     putreg(WUFC),
     putreg(TDBAL),    putreg(TDBAH),    putreg(TXDCTL),   putreg(RDBAH),
     putreg(RDBAL),    putreg(LEDCTL),   putreg(VET),      putreg(FCRUC),

hw/net/e1000e_core.c

@@ -2856,7 +2856,7 @@ e1000e_set_gcr(E1000ECore *core, int index, uint32_t val)
 
 #define e1000e_getreg(x)    [x] = e1000e_mac_readreg
 typedef uint32_t (*readops)(E1000ECore *, int);
-static readops e1000e_macreg_readops[] = {
+static const readops e1000e_macreg_readops[] = {
     e1000e_getreg(PBA),
     e1000e_getreg(WUFC),
     e1000e_getreg(MANC),
@@ -3063,7 +3063,7 @@ enum { E1000E_NREADOPS = ARRAY_SIZE(e1000e_macreg_readops) };
 
 #define e1000e_putreg(x)    [x] = e1000e_mac_writereg
 typedef void (*writeops)(E1000ECore *, int, uint32_t);
-static writeops e1000e_macreg_writeops[] = {
+static const writeops e1000e_macreg_writeops[] = {
     e1000e_putreg(PBA),
     e1000e_putreg(SWSM),
     e1000e_putreg(WUFC),