ARM: shmobile: sh73a0: move SDHI and MMCIF DT nodes to sh73a0.dtsi

To avoid having to repeat common DT node properties in all .dts files
move them to SoC's .dtsi file, setting their status to "disabled."
Individual boards will pick up devices, that they want to use and
change their DT node status to enabled.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>