arm: omap3: Fix omap3_overo SPL boot hangup

Patch f33b9bd3
[arm: omap3: Enable clocks for peripherals only if they are used]
breaks SPL booting on Overo. Since some gpio inputs are
read to detect the board revision. But with this patch above, the
clocks to the GPIO subsystems are not enabled per default any more.
The GPIO banks need to be configured specifically now.

Signed-off-by: Ash Charles <ashcharles@gmail.com>