net: Make setsockopt() optlen be unsigned.

This provides safety against negative optlen at the type
level instead of depending upon (sometimes non-trivial)
checks against this sprinkled all over the the place, in
each and every implementation.

Based upon work done by Arjan van de Ven and feedback
from Linus Torvalds.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ieee802154/raw.c b/net/ieee802154/raw.c
index 1319885..30e74ee 100644
--- a/net/ieee802154/raw.c
+++ b/net/ieee802154/raw.c
@@ -244,7 +244,7 @@
 }
 
 static int raw_setsockopt(struct sock *sk, int level, int optname,
-		    char __user *optval, int optlen)
+		    char __user *optval, unsigned int optlen)
 {
 	return -EOPNOTSUPP;
 }