MDP5 SSPPs can flip the input source horizontally or vertically.
This change is to add this support to MDP5 planes.

v1: Initial change
v2: Use existing "rotation" property instead of creating msm specific
    properties. In order to be compatiable with legacy non-atomic
    set_property, switch to drm_atomic_helper_plane_set_property
    helper function.
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>