ARM: mach-shmobile: Add SDHI support

This patch add SDHI support for G4 board.
Current gpio frame work doesn't have
the method to control only pull-up/down/free.
So, it have special gpio_pull_up function for SDHI.
It is quick hack, so this function should be replaced
by correct gpio frame work in future.

Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>