mmc: Add SuperH to the tmio-mmc Kconfig

Add SUPERH to the Kconfig dependencies for tmio_mmc.

This change allows us to drive the SDHI hardware blocks
found in SuperH Mobile with tmio_mmc.

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