ARM: OMAP: Fix compile for rx51

This fixes a compile error caused by a mismerge while rebasing the patch:

linux-2.6/arch/arm/mach-omap2/board-rx51-peripherals.c:354:
undefined reference to `twl4030_mmc_init'

Looks like I need to also update my build scripts, just grepping for error:
in the logs is not obviously enough..

Signed-off-by: Tony Lindgren <tony@atomide.com>