mx6sabre_common: Place video related settings in common code
Currently mx6sabreauto fails to find the environment variables like this:
## Error: "findfdt" not defined
switch to partitions #0, OK
mmc0 is current device
## Error: "loadbootscript" not defined
## Error: "loadimage" not defined
## Error: "netboot" not defined
Move VIDEO_ARGS/VIDEO_ARGS_SCRIPT so that they can be shared among sabresd
and sabreauto boards.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com> Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
