omap3evm: Fixes after moving to matrix_keypad

The keypad was not working properly after migrating
to matrix_keypad.

Swapped the row, col fields of the KEY() macro in
the keymap definition to get it working again.

Signed-off-by: Sanjeev Premi <premi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>