qed: Add support for vf coalesce configuration.

This patch add the ethtool support to set RX/Tx coalesce
value to the VF associated Rx/Tx queues.

Signed-off-by: Rahul Verma <Rahul.Verma@cavium.com>
Signed-off-by: Yuval Mintz <yuval.mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>