net/rtl8139: update network information when macaddr is changed in guest

rtl8139 has same problem as e1000, nic info isn't updated when macaddr
is changed in guest.

This patch updates the nic info when the last bit of macaddr is written.
Signed-off-by: NAmos Kong <akong@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

hw/net/rtl8139.c

@@ -2741,8 +2741,12 @@ static void rtl8139_io_writeb(void *opaque, uint8_t addr, uint32_t val)
 
     switch (addr)
     {
-        case MAC0 ... MAC0+5:
+        case MAC0 ... MAC0+4:
+            s->phys[addr - MAC0] = val;
+            break;
+        case MAC0+5:
             s->phys[addr - MAC0] = val;
+            qemu_format_nic_info_str(qemu_get_queue(s->nic), s->phys);
             break;
         case MAC0+6 ... MAC0+7:
             /* reserved */