net/mlx4_en: Fix endianness bug in IPV6 csum calculation

net/mlx4_en: Fix endianness bug in IPV6 csum calculation

Orabug: 25308084

[ Upstream commit 82d69203df634b4dfa765c94f60ce9482bcc44d6 ]

Use htons instead of unconditionally byte swapping nexthdr.  On a little
endian systems shifting the byte is correct behavior, but it results in
incorrect csums on big endian architectures.

Fixes: f8c6455bb04b ('net/mlx4_en: Extend checksum offloading by CHECKSUM COMPLETE')
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: Carol Soto <clsoto@us.ibm.com>
Tested-by: Carol Soto <clsoto@us.ibm.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 8bba1625512245771bdb2cb1502697228fe7e1b2)
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>