Revert "drm/ast: Remove reference to struct drm_device.pdev"

Revert "drm/ast: Remove reference to struct drm_device.pdev"

This reverts commit fcb041ca5c7787b096aafc899e45f93583e66cbd which is
commit 0ecb51824e838372e01330752503ddf9c0430ef7 upstream.

Turns out this was incomplete, as it is missing a dependancy, so drop it
from the tree.

Link: https://lore.kernel.org/r/CAJn8CcHHKSo7GF29Z1ufXJJpMUzn6+fdvwiqe9=JvgpcfvnbHQ@mail.gmail.com
Reported-by: Xiaotian Feng <xtfeng@gmail.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Michael J. Ruhl <michael.j.ruhl@intel.com>
Cc: KuoHsiang Chou <kuohsiang_chou@aspeedtech.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dave Airlie <airlied@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>