net: include linux/proc_fs.h in dev_addr_lists.c

As pointed by Randy Dunlap, we must include linux/proc_fs.h in
net/core/dev_addr_lists.c, regardless of CONFIG_PROC_FS

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>,
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>