staging: rtl8712: fix interface sanity check

Make sure to use the current alternate setting when verifying the
interface descriptors to avoid binding to an invalid interface.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: 2865d42 ("staging: r8712u: Add the new driver to the mainline kernel")
Cc: stable <[email protected]>     # 2.6.37
Signed-off-by: Johan Hovold <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: jhovold

drivers/staging/rtl8712/usb_intf.c

@@ -247,7 +247,7 @@ static uint r8712_usb_dvobj_init(struct _adapter *padapter)
 
 	pdvobjpriv->padapter = padapter;
 	padapter->eeprom_address_size = 6;
-	phost_iface = &pintf->altsetting[0];
+	phost_iface = pintf->cur_altsetting;
 	piface_desc = &phost_iface->desc;
 	pdvobjpriv->nr_endpoint = piface_desc->bNumEndpoints;
 	if (pusbd->speed == USB_SPEED_HIGH) {