bonding: Make alb learning packet interval configurable

running bonding in ALB mode requires that learning packets be sent periodically,
so that the switch knows where to send responding traffic.  However, depending
on switch configuration, there may not be any need to send traffic at the
default rate of 3 packets per second, which represents little more than wasted
data.  Allow the ALB learning packet interval to be made configurable via sysfs

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Acked-by: Veaceslav Falico <vfalico@redhat.com>
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_alb.c

@@ -1472,7 +1472,7 @@ void bond_alb_monitor(struct work_struct *work)
 	bond_info->lp_counter++;
 
 	/* send learning packets */
-	if (bond_info->lp_counter >= BOND_ALB_LP_TICKS) {
+	if (bond_info->lp_counter >= BOND_ALB_LP_TICKS(bond)) {
 		/* change of curr_active_slave involves swapping of mac addresses.
 		 * in order to avoid this swapping from happening while
 		 * sending the learning packets, the curr_slave_lock must be held for