omap3evm: Prepare to split configuration

This patch marks the beginning of steps that would
lead to clean and easy split of the configuration
file. Common portion can then be re-used by other
configurations.

Signed-off-by: Sanjeev Premi <premi@ti.com>
Cc: Sandeep Paulraj <s-paulraj@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>