usb: plusb: remove unused pl_clear_QuickLink_features function

clang with W=1 reports
drivers/net/usb/plusb.c:65:1: error:
  unused function 'pl_clear_QuickLink_features' [-Werror,-Wunused-function]
pl_clear_QuickLink_features(struct usbnet *dev, int val)
^
This static function is not used, so remove it.
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/plusb.c

@@ -61,12 +61,6 @@ pl_vendor_req(struct usbnet *dev, u8 req, u8 val, u8 index)
 				val, index, NULL, 0);
 }
 
-static inline int
-pl_clear_QuickLink_features(struct usbnet *dev, int val)
-{
-	return pl_vendor_req(dev, 1, (u8) val, 0);
-}
-
 static inline int
 pl_set_QuickLink_features(struct usbnet *dev, int val)
 {