drm/msm/sde: add support for ROTATE_0 to plane

Plane rotate angle of zero can be specified with 0
or ROTATE_0 in plane rotation property. 0 is already
supported by plane driver. Add support for ROTATE_0
to plane driver. Without this support, ROTATE_0 will
generate incorrectly flipped image.

CRs-Fixed: 2009714
Change-Id: Ic6c6a0a2a24bb7c544c191c26dace788d30cc69d
Signed-off-by: Alan Kwong <akwong@codeaurora.org>