drm/msm/dp: Allow sub-regions to be specified in DT

drm/msm/dp: Allow sub-regions to be specified in DT

Not all platforms has P0 at an offset of 0x1000 from the base address,
so add support for specifying each sub-region in DT. The code falls back
to the predefined offsets in the case that only a single reg is
specified, in order to support existing DT.

Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211001174400.981707-6-bjorn.andersson@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>