Drop use of the deprecated drmP.h header file.
Fix fallout in all .c files.

The etnaviv_drv.h header file was made self-contained,
and missing includes was then added to the .c files that needed them.
In a few cases the list of include files was sorted.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: etnaviv@lists.freedesktop.org
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>