ARM: sunxi: Add support for Allwinner SUNXi SoCs sata to ahci_platform

This patch adds support for the ahci sata controler found on Allwinner A10
and A20 SoCs to the ahci_platform driver.

Orignally written by Olliver Schinagl using the approach of having a platform
device which probe method creates a new child platform device which gets
driven by ahci_platform.c, as done by ahci_imx.c .

Refactored by Hans de Goede to add most of the non sunxi specific functionality
to ahci_platform.c and use a platform_data pointer from of_device_id for the
sunxi specific bits.

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