mwifiex: corner case NULL pointer dereference fix

When next scan command is delayed due to Tx traffic and
meanwhile synchronous command is received followed by a signal,
we cance all pending commands. NULL pointer dereference is seen
in this case while queueing next command in scan delay timer.
This patch adds a check to fix this issue.
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/main.c

@@ -38,7 +38,8 @@ static void scan_delay_timer_fn(unsigned long data)
 	if (adapter->surprise_removed)
 		return;
 
-	if (adapter->scan_delay_cnt == MWIFIEX_MAX_SCAN_DELAY_CNT) {
+	if (adapter->scan_delay_cnt == MWIFIEX_MAX_SCAN_DELAY_CNT ||
+	    !adapter->scan_processing) {
 		/*
 		 * Abort scan operation by cancelling all pending scan
 		 * commands