neigh: Move neigh_compat_output into ax25_ip.c

The only caller is now is ax25_neigh_construct so move
neigh_compat_output into ax25_ip.c make it static and rename it
ax25_neigh_output.

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-hams@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc include/net/neighbour.h
Simple merge

diff --cc net/ax25/ax25_ip.c
Simple merge

diff --cc net/core/neighbour.c
Simple merge