mx6qsabreauto: Change mmcroot so it works out of box

The mmcroot setting vary between mx6qsabreauto and mx6qsabresd so we
move this to the board configuration file.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Acked-by: Fabio Estevam <fabio.estevam@freescale.com>
3 files changed