USB: mark "reject" field of struct urb as atomic_t

It is enough to protect accesses to reject field of urb
by marking it as atomic_t,also it is the only reason of
existence of usb_reject_lock,so remove the lock to make
code more clean.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/usb.h b/include/linux/usb.h
index e9d6356..4e8654a 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1340,7 +1340,7 @@
 	struct kref kref;		/* reference count of the URB */
 	void *hcpriv;			/* private data for host controller */
 	atomic_t use_count;		/* concurrent submissions counter */
-	u8 reject;			/* submissions will fail */
+	atomic_t reject;		/* submissions will fail */
 	int unlinked;			/* unlink error code */
 
 	/* public: documented fields in the urb that can be used by drivers */