drm/msm/dpu: access CSC/CSC10 registers directly

Stop using _sspp_subblk_offset() to get offset of the csc_blk. Inline
this function and use ctx->cap->sblk->csc_blk.base directly.

As this was the last user, drop _sspp_subblk_offset() too.

Reviewed-by: Jeykumar Sankaran <quic_jeykumar@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/534747/
Link: https://lore.kernel.org/r/20230429012353.2569481-4-dmitry.baryshkov@linaro.org


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