net: Cleanup redundant tests on unsigned

If there is data, the unsigned skb->len is greater than 0.

rt.sigdigits is unsigned as well, so the test `>= 0' is
always true, the other part of the test catches wrapped
values.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/x25/x25_in.c b/net/x25/x25_in.c
index 7d7c3ab..96d9227 100644
--- a/net/x25/x25_in.c
+++ b/net/x25/x25_in.c
@@ -114,7 +114,7 @@
 			/*
 			 *	Copy any Call User Data.
 			 */
-			if (skb->len >= 0) {
+			if (skb->len > 0) {
 				skb_copy_from_linear_data(skb,
 					      x25->calluserdata.cuddata,
 					      skb->len);