net/atm/lec.c: Add __lec_arp_check_expire and other cleanups

Reduce indentation in lec_arp_check_expire
Indent a case label
Remove != NULL logical tests from while ((skb = foo())) assign and tests

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>