drm/msm/mdss: use register definitions instead of hand-coding them

Move existing register definitions to mdss.xml and use generated defines
for registers access instead of hand-coding everything in the source
file.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/615312/
Link: https://lore.kernel.org/r/20240921-msm-mdss-ubwc-v1-2-411dcf309d05@linaro.org