[ARM] 3678/1: MMC: Make OMAP MMC work

Patch from Tony Lindgren

This patch makes OMAP MMC work again:

- Fix compile errors
- Do not ioremap base as it is already statically mapped
- Clean-up platform device handling
- Fix compile warnings

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>