gpu/drm: Remove duplicate headers

Remove duplicate headers which are included twice.

Signed-off-by: Jagadeesh Pagadala <jagdsh.linux@gmail.com>
Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Dave Airlie <airlied@linux.ie>
[danvet: drop changes to panel-raspberrypi, they break the build]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1556906293-128921-1-git-send-email-jagdsh.linux@gmail.com