ARM: IMX31: configure pins iomux for SDHC setup on litekit board.

This patch adds SDHC support, and corrects current pins setup.
Added irq handling on card removal.

Signed-off-by: Vladimir Zapolskiy <vzapolskiy@gmail.com>
Cc: Daniel Mack <daniel@caiaq.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>