brcmfmac: Ignore E_ADD_IF for ifidx 0.

All interfaces for ifidx is 0 are created ahead and therefor
double registrations for not only bssidx 0, but ifidx 0 should
be ignored in brcfm_add_if.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/brcm80211/brcmfmac/dhd_linux.c

@@ -716,7 +716,7 @@ struct brcmf_if *brcmf_add_if(struct brcmf_pub *drvr, s32 bssidx, s32 ifidx,
 	if (ifp) {
 		brcmf_err("ERROR: netdev:%s already exists\n",
 			  ifp->ndev->name);
-		if (bssidx) {
+		if (ifidx) {
 			netif_stop_queue(ifp->ndev);
 			unregister_netdev(ifp->ndev);
 			free_netdev(ifp->ndev);