vxlan: fix indentation

Some lines in vxlan code are indented by 7 spaces instead of a tab.

Fixes: e4c7ed41 ("vxlan: add ipv6 support")
Signed-off-by: NJiri Benc <jbenc@redhat.com>
Acked-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>