mx6cuboxi: Add support for sata

The Cubox-i and Hummingboard series of devices have an option of
SATA on board, and depending on how the fuses are blown even the
option to boot SPL from SATA. So enable support for it so it can
be used to boot the OS from if people desire.

Cc: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Acked-by: Fabio Estevam <fabio.estevam@nxp.com>