configs: Remove unnecessary options from RGxx3 config

Based on feedback from the mailing list while adding support for a new
device (the Powkiddy X55), correct the config options for the RGxx3
as well to remove unnecessary drivers and increase the SPL stack size.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>