staging: rtl8192u: Replace mdelay with msleep in rtl8192_usb_probe

rtl8192_usb_probe is not called in an interrupt handler
nor holding a spinlock.
The function mdelay in it can be replaced with msleep,
to avoid busy wait.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>

drivers/staging/rtl8192u/r8192U_core.c

@@ -4998,7 +4998,7 @@ static int rtl8192_usb_probe(struct usb_interface *intf,
 	kfree(priv->pFirmware);
 	priv->pFirmware = NULL;
 	rtl8192_usb_deleteendpoints(dev);
-	mdelay(10);
+	msleep(10);
 	free_ieee80211(dev);
 
 	RT_TRACE(COMP_ERR, "wlan driver load failed\n");