mwifiex: Replace semaphore async_sem with mutex

The semaphore 'async_sem' is used as a simple mutex, so
it should be written as one. Semaphores are going away in the future.
Signed-off-by: Binoy Jayan <binoy.jayan@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/cfg80211.c

@@ -3033,7 +3033,7 @@ struct wireless_dev *mwifiex_add_virtual_intf(struct wiphy *wiphy,
 	INIT_DELAYED_WORK(&priv->dfs_chan_sw_work,
 			  mwifiex_dfs_chan_sw_work_queue);
 
-	sema_init(&priv->async_sem, 1);
+	mutex_init(&priv->async_mutex);
 
 	/* Register network device */
 	if (register_netdevice(dev)) {

drivers/net/wireless/marvell/mwifiex/main.h

@@ -629,7 +629,7 @@ struct mwifiex_private {
 	struct dentry *dfs_dev_dir;
 #endif
 	u16 current_key_index;
-	struct semaphore async_sem;
+	struct mutex async_mutex;
 	struct cfg80211_scan_request *scan_request;
 	u8 cfg_bssid[6];
 	struct wps wps;

drivers/net/wireless/marvell/mwifiex/scan.c

@@ -2809,7 +2809,7 @@ int mwifiex_request_scan(struct mwifiex_private *priv,
 {
 	int ret;
 
-	if (down_interruptible(&priv->async_sem)) {
+	if (mutex_lock_interruptible(&priv->async_mutex)) {
 		mwifiex_dbg(priv->adapter, ERROR,
 			    "%s: acquire semaphore fail\n",
 			    __func__);
@@ -2825,7 +2825,7 @@ int mwifiex_request_scan(struct mwifiex_private *priv,
 		/* Normal scan */
 		ret = mwifiex_scan_networks(priv, NULL);
 
-	up(&priv->async_sem);
+	mutex_unlock(&priv->async_mutex);
 
 	return ret;
 }