omap3evm: add support for the WL12xx WLAN module to the AM/DM3xx Evaluation Module

Adds platform initialization for working with the WLAN module attached to the evaluation module.
The patch includes MMC2 initialization, SDIO and control pins muxing and platform device registration

Signed-off-by: Eyal Reizer <eyalr@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>