drm/mxsfb: drop use of drmP.h

Drop use of the deprecated drmP.h header file.

While touching the list of include files divided them
in blocks and sort them within each block.
Fixed fallout in the relevant files.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Stefan Agner <stefan@agner.ch>
Acked-by: Emil Velikov <emil.velikov@collabora.com>
Cc: Marek Vasut <marex@denx.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://patchwork.freedesktop.org/patch/msgid/20190630061922.7254-6-sam@ravnborg.org