drm/msm/dpu: rename struct dpu_hw_pipe(_cfg) to dpu_hw_sspp(_cfg)

drm/msm/dpu: rename struct dpu_hw_pipe(_cfg) to dpu_hw_sspp(_cfg)

For all hardware blocks except SSPP the corresponding struct is named
after the block. Rename dpu_hw_pipe (SSPP structure) to dpu_hw_sspp.
Also rename struct dpu_hw_pipe_cfg to dpu_hw_sspp_cfg to follow this
change.

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/527312/
Link: https://lore.kernel.org/r/20230316161653.4106395-2-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>