rtl8192u: Remove unused semaphore rf_sem

The semaphore 'rf_sem' in rtl8192u has no users, hence removing it.
Signed-off-by: Binoy Jayan <binoy.jayan@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/r8192U.h

@@ -880,7 +880,6 @@ typedef struct r8192_priv {
 	short crcmon;
 
 	struct mutex wx_mutex;
-	struct semaphore rf_sem;	/* Used to lock rf write operation */
 
 	u8 rf_type;			/* 0: 1T2R, 1: 2T4R */
 	RT_RF_TYPE_819xU rf_chip;

drivers/staging/rtl8192u/r8192U_core.c

@@ -2377,7 +2377,6 @@ static void rtl8192_init_priv_lock(struct r8192_priv *priv)
 	spin_lock_init(&priv->tx_lock);
 	spin_lock_init(&priv->irq_lock);
 	mutex_init(&priv->wx_mutex);
-	sema_init(&priv->rf_sem, 1);
 	mutex_init(&priv->mutex);
 }