[ATM]: atm/mpc.c warning fix

net/atm/mpc.c: In function 'MPOA_res_reply_rcvd':
net/atm/mpc.c:1116: warning: unused variable 'ip'

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>