drm_plane_helper_check_update() needs to account for the plane rotation
for correct clipping/scaling calculations. Do so.

There was an earlier attempt [1] to add this into
intel_check_primary_plane() but I requested that it'd be put into the
helper instead. An updated patch never materialized AFAICS, so I went
ahead and cooked one up myself.

v2: Deal with new drm_plane_helper_check_update() callers

[1] https://patchwork.freedesktop.org/patch/65177/
Cc: Nabendu Maiti <nabendu.bikash.maiti@intel.com>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: CK Hu <ck.hu@mediatek.com>
Cc: Mark Yao <mark.yao@rock-chips.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NPatrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1466172790-10025-1-git-send-email-ville.syrjala@linux.intel.com

It's unused, and really this helper should only look at the state
structure and nothing else.

v2: Fix commit message (Laurent).

v3: Rebase onto mtk driver merge.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Mark Yao <mark.yao@rock-chips.com>
Acked-by: NThierry Reding <thierry.reding@gmail.com>
Acked-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1462804451-15318-2-git-send-email-daniel.vetter@ffwll.ch

This patch adds an initial DRM driver for the Mediatek MT8173 DISP
subsystem. It currently supports two fixed output streams from the
OVL0/OVL1 sources to the DSI0/DPI0 sinks, respectively.
Signed-off-by: NCK Hu <ck.hu@mediatek.com>
Signed-off-by: NYT Shen <yt.shen@mediatek.com>
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Signed-off-by: NBibby Hsieh <bibby.hsieh@mediatek.com>
Signed-off-by: NMao Huang <littlecvr@chromium.org>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>