[PATCH] bonding: Sparse warnings fix

drivers/net/bonding/bond_sysfs.c:263:27: warning: Using plain integer as NULL pointer
drivers/net/bonding/bond_sysfs.c:998:26: warning: Using plain integer as NULL pointer
drivers/net/bonding/bond_sysfs.c:1126:26: warning: Using plain integer as NULL pointer

Signed-off-by: Luiz Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>