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