sunhme: fix incorrect constant in sunhme_can_receive()

Due to a copy/paste error the wrong register was being checked in order to
determine if the NIC is able to receive data.
Signed-off-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

hw/net/sunhme.c

@@ -649,7 +649,7 @@ static int sunhme_can_receive(NetClientState *nc)
 {
     SunHMEState *s = qemu_get_nic_opaque(nc);
 
-    return s->macregs[HME_MAC_RXCFG_ENABLE >> 2] & HME_MAC_RXCFG_ENABLE;
+    return s->macregs[HME_MACI_RXCFG >> 2] & HME_MAC_RXCFG_ENABLE;
 }
 
 static void sunhme_link_status_changed(NetClientState *nc)