drm/msm/dp: Store each subblock in the io region

Not all platforms has DP_P0 at offset 0x1000 from the beginning of the
DP block. So split the dss_io_data memory region into a set of
sub-regions, to make it possible in the next patch to specify each of
the sub-regions individually.

Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211001174400.981707-5-bjorn.andersson@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>