am33xx/am43xx: Add platform data for GPIOs

am33xx/am43xx: Add platform data for GPIOs

On these platforms we have many cases of boards that enable device model
and GPIO support but do not enable OF_CONTROL and pass in a device tree
with the binary.  We need to bring in the platform data here as well.

Tested on Beaglebone Black.

Reported-by: Robert Nelson <robertcnelson@gmail.com>
Reported-by: Francisco Aguerre <franciscoaguerre@gmail.com>
Reported-by: Jason Kridner <jkridner@beagleboard.org>
Signed-off-by: Tom Rini <trini@konsulko.com>