lcd: split configuration_get_cmap

lcd: split configuration_get_cmap

configuration_get_cmap() is multiple platform-specific functions stuffed into
one function. Split it into multiple versions, and move each version to the
appropriate driver to reduce the #ifdef complexity.

Signed-off-by: Nikita Kiryanov <[email protected]>
Reviewed-by: Simon Glass <[email protected]>
Tested-by: Bo Shen <[email protected]>
Tested-by: Josh Wu <[email protected]>
Cc: Bo Shen <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: Anatolij Gustschin <[email protected]>