drm/msm/dpu: move pipe_hw to dpu_plane_state

drm/msm/dpu: move pipe_hw to dpu_plane_state

In preparation to adding fully virtualized planes, move struct
dpu_hw_sspp instance from struct dpu_plane to struct dpu_plane_state, as
it will become a part of state (variable, changes during runtime) rather
than part of a plane (ideally should be statically allocated during boot).

The sspp pointer is set at the dpu_plane_reset(), since this is the
function which allocates the state. Once we have fully virtual
plane<->SSPP relationship, the SSPP will be allocated dynamically in the
dpu_plane_atomic_check() function.

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Tested-by: Abhinav Kumar <quic_abhinavk@quicinc.com> # sc7280
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/527322/
Link: https://lore.kernel.org/r/20230316161653.4106395-6-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>