Exynos: Split 5250 and 5420 memory bank configuration

Exynos: Split 5250 and 5420 memory bank configuration

Since snow has a different memory configuration than peach, split the
configuration between the 5250 and 5420. Exynos 5420 supports runtime
memory configuration detection, and can make the determination between 4
and 7 banks at runtime.

Include the bank size with the number of banks for context to make the
number of banks meaningful.

Signed-off-by: Michael Pratt <[email protected]>
Signed-off-by: Akshay Saraswat <[email protected]>
Acked-by: Simon Glass <[email protected]>
Tested-by: Simon Glass <[email protected]>
Signed-off-by: Minkyu Kang <[email protected]>