mx6sx: Add initial support for UDOO Neo Board

UDOO Neo Board is a development board from Seco that has three models:
 - UDOO Neo Basic
 - UDOO Neo Basic Kick Starter
 - UDOO Neo Extended
 - UDOO Neo Full

All versions are based on the i.MX6 SoloX processor.

For more details about the UDOO Neo board, please refer to:
http://www.udoo.org/udoo-neo/

This work is based on a previous commit of Francesco Montefoschi
<francesco.monte@gmail.com>:
https://github.com/fmntf/u-boot/commit/877b71184a5105e708024f232d36aed574961844



Only tested on the UDOO Neo Full board.

Signed-off-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>