Added CuBox 2GB support

U-boot build now builds for 1GB and 2GB base systems.

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>
Add 512MB DDR support

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>
Different memory configs supports

1. Removed 512MB support
2. Created new DDR config for unifieid u-boot SPI version for both CuBox and CuBox pro.
3. The uart version of u-boot (one used to unbrick) can't be unified and the user needs
   to know which system he/she has and accordingly use the right u-boot uart version.

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>
Merge branch 'master' of github.com:rabeeh/u-boot