wlcore: consider single fw case

When a single fw is being used for both single-role
and multi-role cases (e.g. 18xx), wl->mr_fw_name is
NULL, which results in NULL dereference while trying
to load the multi-role fw.

In this case, always use the single-role fw, and avoid
redundant fw switch by checking for this case in
wl12xx_need_fw_change() as well.
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <luca@coelho.fi>

drivers/net/wireless/ti/wlcore/main.c

@@ -696,7 +696,7 @@ static int wl12xx_fetch_firmware(struct wl1271 *wl, bool plt)
 		 * we can't call wl12xx_get_vif_count() here because
 		 * wl->mutex is taken, so use the cached last_vif_count value
 		 */
-		if (wl->last_vif_count > 1) {
+		if (wl->last_vif_count > 1 && wl->mr_fw_name) {
 			fw_type = WL12XX_FW_TYPE_MULTI;
 			fw_name = wl->mr_fw_name;
 		} else {
@@ -2170,6 +2170,10 @@ static bool wl12xx_need_fw_change(struct wl1271 *wl,
 	if (wl->state == WL1271_STATE_OFF)
 		return false;
 
+	/* no need for fw change if a single fw is used */
+	if (!wl->mr_fw_name)
+		return false;
+
 	if (vif_count > 1 && current_fw == WL12XX_FW_TYPE_NORMAL)
 		return true;
 	if (vif_count <= 1 && current_fw == WL12XX_FW_TYPE_MULTI)