nfc: signedness bug in __nci_request()

wait_for_completion_interruptible_timeout() returns -ERESTARTSYS if
interrupted so completion_rc needs to be signed.  The current code
probably returns -ETIMEDOUT if we hit this situation, but after this
patch is applied it will return -ERESTARTSYS.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/nfc/nci/core.c

@@ -68,7 +68,7 @@ static int __nci_request(struct nci_dev *ndev,
 	__u32 timeout)
 {
 	int rc = 0;
-	unsigned long completion_rc;
+	long completion_rc;
 
 	ndev->req_status = NCI_REQ_PEND;