drm/mediatek: Set the default value of rotation to DRM_MODE_ROTATE_0

At the reset hook, call __drm_atomic_helper_plane_reset which is
called at the initialization of the plane and sets the default value of
rotation on all planes to DRM_MODE_ROTATE_0 which is equal to 1.

Tested on Jacuzzi (MTK).
Resolves IGT@kms_properties@plane-properties-{legacy,atomic}

Signed-off-by: Mark Yacoub <markyacoub@chromium.org>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>