drm/msm: get rid of msm_iomap_size

Instead of looping throught the resources each time to get the DSI CTRL
area size, get it at the ioremap time.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Link: https://lore.kernel.org/r/20210427001828.2375555-4-dmitry.baryshkov@linaro.org


Signed-off-by: Rob Clark <robdclark@chromium.org>