bonding: migrate some macros from bond_alb.c to bond_alb.h

This patch simply migrates some macros from bond_alb.c to bond_alb.h.

Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>