ARM: davinci: board-omapl138-hawk: fix GPIO numbers for MMC/SD lookup

commit c4dc56be ("ARM: davinci: fix the GPIO lookup for omapl138-hawk")
fixed the GPIO chip name for look-up of MMC/SD CD and WP pins, but forgot
to change the GPIO numbers passed.

The GPIO numbers are not offsets from within a 32 GPIO bank. Fix the
GPIO numbers as well as remove the misleading comment.

Fixes: c4dc56be ("ARM: davinci: fix the GPIO lookup for omapl138-hawk")
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>