brcmfmac: fix NULL pointer access in brcmf_create_iovar()

The function brcmf_fil_bsscfg_data_get() calls brcmf_create_iovar()
with data pointer set to NULL, which caused a NULL pointer access.
As it should be possible to provide data in message towards the
firmware, it should just pass the data buffer instead.

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

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

@@ -294,7 +294,7 @@ brcmf_fil_bsscfg_data_get(struct brcmf_if *ifp, char *name,
 
 	mutex_lock(&drvr->proto_block);
 
-	buflen = brcmf_create_bsscfg(ifp->bssidx, name, NULL, len,
+	buflen = brcmf_create_bsscfg(ifp->bssidx, name, data, len,
 				     drvr->proto_buf, sizeof(drvr->proto_buf));
 	if (buflen) {
 		err = brcmf_fil_cmd_data(ifp, BRCMF_C_GET_VAR, drvr->proto_buf,