Use the the DRM driver for MXSFB LCD controller (used in i.MX23/
i.MX28/i.MX6SX or i.MX7). Remove CONFIG_FB_MXS which will soon be
removed.
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>