drmP.h is deprecated and will be deleted.
Replace use with proper header.

Divide header includes in blocks while touching these.

Build tested with various archtectures and configs.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Fixes: ae85b0df ("drm_dp_cec: add connector info support.")
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Sean Paul <sean@poorly.run>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Dariusz Marcinkiewicz <darekm@google.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191007171224.1581-2-sam@ravnborg.org