staging: rtl8192u: Deleted 'rtl8192_beacon_stop' function in r8192U_core.c

This patch delete the 'rtl8192_beacon_stop' function that is not used
in anywhere in the driver.

Fix the following sparse warning in r8192U_core.c

drivers/staging/rtl8192u/r8192U_core.c:1332:6: warning: symbol 'rtl8192_beacon_stop' was not declared. Should it be static?
Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>

drivers/staging/rtl8192u/r8192U_core.c

@@ -1329,24 +1329,6 @@ static void rtl8192_tx_isr(struct urb *tx_urb)
 
 }
 
-void rtl8192_beacon_stop(struct net_device *dev)
-{
-	u8 msr, msrm, msr2;
-	struct r8192_priv *priv = ieee80211_priv(dev);
-
-	read_nic_byte(dev, MSR, &msr);
-	msrm = msr & MSR_LINK_MASK;
-	msr2 = msr & ~MSR_LINK_MASK;
-
-	if (NIC_8192U == priv->card_8192)
-		usb_kill_urb(priv->rx_urb[MAX_RX_URB]);
-	if ((msrm == (MSR_LINK_ADHOC<<MSR_LINK_SHIFT) ||
-	    (msrm == (MSR_LINK_MASTER<<MSR_LINK_SHIFT)))) {
-		write_nic_byte(dev, MSR, msr2 | MSR_LINK_NONE);
-		write_nic_byte(dev, MSR, msr);
-	}
-}
-
 static void rtl8192_config_rate(struct net_device *dev, u16 *rate_config)
 {
 	struct r8192_priv *priv = ieee80211_priv(dev);