drm/arm: drop use of drmP.h

Drop use of the deprecated drmP.h header file.

While touching the list of include files divide them
into blocks and sort within each block.
Fix fallout.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Brian Starkey <brian.starkey@arm.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: malidp@foss.arm.com
Link: https://patchwork.freedesktop.org/patch/msgid/20190804094132.29463-5-sam@ravnborg.org