Odroid-XU3: dts: enable ADC, with request for pre-reloc bind

This ADC is required for Odroid's board revision detection.
The pre-reloc request is enabled, since board detection will
be done in one of early function call.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>