drm/ast: drop use of drmP.h

Drop use of the deprecated drmP.h header file.
While touching the files divide include files in blocks
and sort the include files in the individual blocks.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Emil Velikov <emil.velikov@collabora.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Sam Bobroff <sbobroff@linux.ibm.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: "Y.C. Chen" <yc_chen@aspeedtech.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190630061922.7254-33-sam@ravnborg.org