drm/virtio: remove drm_plane_cleanup() destroy hook

drmm_universal_plane_alloc() already registers drm_plane_cleanup() as
managed release action via drmm_add_action_or_reset(). Hence,
drm_plane_cleanup() should not be set as drm_plane_funcs.destroy hook.

Fixes: 78476288 ("drm/virtio: plane: use drm managed resources")
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220803145520.1143208-1-dakr@redhat.com