bonding: fix u64 division

After the option conversion downdelay and updelay divide a u64
and on a 32 bit this causes the following errors:
ERROR: "__udivdi3" [drivers/net/bonding/bonding.ko] undefined!
ERROR: "__umoddi3" [drivers/net/bonding/bonding.ko] undefined!

Fix it by using a normal int instead because newval->value is capped
at INT_MAX by the way the option is defined.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>