Staging: rtl8712: signedness bug in init

PollingCnt is 20 and that means we loop 20 times and then run the
timeout code.  After the end of the loop PollingCnt should be -1 but
because it's an unsigned char, it's actually 255 and the timeout
code never runs.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/rtl8712/usb_halinit.c

@@ -37,7 +37,7 @@ u8 r8712_usb_hal_bus_init(struct _adapter *padapter)
 {
 	u8 val8 = 0;
 	u8 ret = _SUCCESS;
-	u8 PollingCnt = 20;
+	int PollingCnt = 20;
 	struct registry_priv *pregistrypriv = &padapter->registrypriv;
 
 	if (pregistrypriv->chip_version == RTL8712_FPGA) {