net: xfrm: xfrm_policy: fix inline not at beginning of declaration

Fix three warnings related to:

  net/xfrm/xfrm_policy.c:1644:1: warning: 'inline' is not at beginning of declaration [-Wold-style-declaration]
  net/xfrm/xfrm_policy.c:1656:1: warning: 'inline' is not at beginning of declaration [-Wold-style-declaration]
  net/xfrm/xfrm_policy.c:1668:1: warning: 'inline' is not at beginning of declaration [-Wold-style-declaration]

Just removing the inline keyword is sufficient as the compiler will
decide on its own about inlining or not.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>