mmc: tmio-mmc: parse device-tree bindings

Add parsing of common and driver-specific DT bindings to the tmio-mmc
MMC host driver and the sh_mobile_sdhi interface layer.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>