mmc: sunxi: Add driver for SD/MMC hosts found on Allwinner sunxi SoCs

mmc: sunxi: Add driver for SD/MMC hosts found on Allwinner sunxi SoCs

The Allwinner sunxi mmc host uses dma in bus-master mode using a built-in
designware idmac controller, which is identical to the one found in the mmc-dw
hosts. However the rest of the host is not identical to mmc-dw, it deals with
sending stop commands in hardware which makes it significantly different
from the mmc-dw devices.

Signed-off-by: David Lanzendörfer <[email protected]>
[[email protected]: various cleanups and fixes]
Signed-off-by: Hans de Goede <[email protected]>
Acked-by: Maxime Ripard <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Signed-off-by: Ulf Hansson <[email protected]>
Acked-by: Chris Ball <[email protected]>
Signed-off-by: Mike Turquette <[email protected]>