vxlan: include net/ip6_checksum.h for csum_ipv6_magic()
vxlan: include net/ip6_checksum.h for csum_ipv6_magic()

Fengguang reported a compile warning:

   drivers/net/vxlan.c: In function 'vxlan6_xmit_skb':
   drivers/net/vxlan.c:1352:3: error: implicit declaration of function 'csum_ipv6_magic' [-Werror=implicit-function-declaration]
   cc1: some warnings being treated as errors

this patch fixes it.

Reported-by: kbuild test robot <24f7fe9d205c8a9f6ade0c2894e14303ca16087f@intel.com>
Signed-off-by: Cong Wang <b08afa93ec8eabe95bc97d12956ca699fa65834c@redhat.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs