drm/msm/dpu: change catalog->dma_cfg to be a const pointer

Change dpu_mdss_cfg::dma_cfg to be a const pointer rather than embedding
the dpu_reg_dma_cfg struct into the struct dpu_mdss_cfg.

Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/488162/
Link: https://lore.kernel.org/r/20220602202447.1755115-6-dmitry.baryshkov@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>