ipv6: Pass proto to csum_ipv6_magic as __u8 instead of unsigned short

This patch updates csum_ipv6_magic so that it correctly recognizes that
protocol is a unsigned 8 bit value.

This will allow us to better understand what limitations may or may not be
present in how we handle the data.  For example there are a number of
places that call htonl on the protocol value.  This is likely not necessary
and can be replaced with a multiplication by ntohl(1) which will be
converted to a shift by the compiler.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_checksum.c b/net/ipv6/ip6_checksum.c
index 8f920580..b2025bf 100644
--- a/net/ipv6/ip6_checksum.c
+++ b/net/ipv6/ip6_checksum.c
@@ -6,8 +6,7 @@
 #ifndef _HAVE_ARCH_IPV6_CSUM
 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 			const struct in6_addr *daddr,
-			__u32 len, unsigned short proto,
-			__wsum csum)
+			__u32 len, __u8 proto, __wsum csum)
 {
 
 	int carry;