qed: Add support for coalescing config read/update.

This patch adds support for configuring the device tx/rx coalescing
timeout values in the order of micro seconds. It also adds APIs for
upper layer drivers for reading/updating the coalescing values.

Signed-off-by: Sudarsana Reddy Kalluru <sudarsana.kalluru@qlogic.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>