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