ahci-platform: Add support for devices with more then 1 clock

The allwinner-sun4i AHCI controller needs 2 clocks to be enabled and the
imx AHCI controller needs 3 clocks to be enabled.

tj: Minor comment formatting updates.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>