drm/atmel_hlcdc: drop use of drmP.h

Drop use of the deprecated header drmP.h.
Make header file self-contained, with only the required set
of include files.
And fixed fallout in remaining files.
Divide include files in blocks and sort them within each block.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Emil Velikov <emil.velikov@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://patchwork.freedesktop.org/patch/msgid/20190630061922.7254-15-sam@ravnborg.org