drm/msm/dsi: replace PHY's init callback with configurable data

DSI PHY init callback would either map dsi_phy_regulator or dsi_phy_lane
depending on the PHY type. Replace those callbacks with configuration
options governing mapping those regions.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Tested-by: Stephen Boyd <swboyd@chromium.org> # on sc7180 lazor
Link: https://lore.kernel.org/r/20210331105735.3690009-4-dmitry.baryshkov@linaro.org
Signed-off-by: Rob Clark <robdclark@chromium.org>