[NET]: sparse warning fixes

Fix a bunch of sparse warnings. Mostly about 0 used as
NULL pointer, and shadowed variable declarations.
One notable case was that hash size should have been unsigned.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index d27ee8c..8228b57 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -107,7 +107,7 @@
 	 */
 	struct inet_bind_hashbucket	*bhash;
 
-	int				bhash_size;
+	unsigned int			bhash_size;
 	unsigned int			ehash_size;
 
 	/* All sockets in TCP_LISTEN state will be in here.  This is the only