ARM: mach-shmobile: SDHI0 GPIO hotplug for AG5EVM

Implement GPIO hotplugging via TMIO_MMC_HAS_COLD_CD for
AG5EVM SDHI0. This is possible now when INTCA is used for
IRQ triggering on sh73a0. Without INTCA IRQ support we are
left with the GIC hardware block that does not support
dealing with active low interrupt sources.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>