omap3: evm: make HSMMC driver built-in

For ease of use it is preferrable to build in HSMMC driver
rather than build it as kernel module. This patches updates
default configuration for omap3evm to reflect this change.

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