ARM: ep93xx: simone: support for SPI-based MMC/SD cards

This includes setting up EGPIOs 0 and 9 for card detection and
chip select respectively. This patch is needed to mount a root
filesystem on the SPI-based MMC card reader found on the Sim.One.

Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>