ax25: Stop using sock->sk_protinfo.

Just make a ax25_sock structure that provides the ax25_cb pointer.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc include/net/ax25.h
Simple merge

diff --cc net/ax25/af_ax25.c
Simple merge

diff --cc net/ax25/ax25_in.c
Simple merge