hw/net/dp8393x: don't make prom region 'nomigrate'

Currently we use memory_region_init_rom_nomigrate() to create
the "dp3893x-prom" memory region, and we don't manually register
it with vmstate_register_ram(). This currently means that its
contents are migrated but as a ram block whose name is the empty
string; in future it may mean they are not migrated at all. Use
memory_region_init_ram() instead.

Note that this is a a cross-version migration compatibility break
for the MIPS "magnum" and "pica61" machines.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NAleksandar Markovic <aleksandar.markovic@wavecomp.com>
Message-id: 20180706174309.27110-1-peter.maydell@linaro.org

hw/net/dp8393x.c

@@ -887,7 +887,7 @@ static void dp8393x_realize(DeviceState *dev, Error **errp)
     s->watchdog = timer_new_ns(QEMU_CLOCK_VIRTUAL, dp8393x_watchdog, s);
     s->regs[SONIC_SR] = 0x0004; /* only revision recognized by Linux */
 
-    memory_region_init_ram_nomigrate(&s->prom, OBJECT(dev),
+    memory_region_init_ram(&s->prom, OBJECT(dev),
                            "dp8393x-prom", SONIC_PROM_SIZE, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);