sh: sh7724 Enable SDIO IRQs

This patch enables the interrupt generation for SDIO IRQs
of the sdhi controllers of the SoC. To make sure interrupt
are handled announce the MMC_CAP_SDIO_IRQ capability
on ecovec, kfr2r09 and se7724.

Tested with a b43-based SDIO wireless card on ecovec.

Signed-off-by: Arnd Hannemann <arnd@arndnet.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>