According to drm_plane_create_zpos_property() function documentation,
all planes zpos range should be set if zpos property is supported.
However, the rcar-du driver didn't set primary plane zpos range. Since
the primary plane's zpos is fixed, set it immutably.
Reported-by: NYoshihito Ogawa <yoshihito.ogawa.kc@renesas.com>
Reported-by: NKoji Matsuoka <koji.matsuoka.xm@renesas.com>
Signed-off-by: NTomohito Esaki <etom@igel.co.jp>
Reviewed-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: NDaniel Stone <daniels@collabora.com>
[Turn continue into if ... else ...]
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>