omap: omap3evm: add support for the WL12xx WLAN module to the omap3evm

This patch is again current omap-for-linus branch

Adds platform initialization for working with the WLAN module
attached to the omap3evm.
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>