ARM: shmobile: armadillo800eva: add a fixed voltage regulator for SDHI1

The SDHI1 power supply on armadillo800eva can be switched on and off. In
the current version this is not used and the regulator is hard-wired to
"on." This patch switches SDHI1 to a proper fixed-voltage regulator,
using a GPIO to enable and disable it. Both SDHI0 and SDHI1 ports shall
now be specifying the MMC_CAP_POWER_OFF_CARD MMC capability. Both
interfaces tested with an SDIO card.

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