drm/msm/dpu: drop unused variable from dpu_kms_mdp_snapshot()

drm/msm/dpu: drop unused variable from dpu_kms_mdp_snapshot()

Follow up the merge of address fields and drop the variable that became
unused after the commit 9403f9a42c88 ("drm/msm/dpu: merge base_off with
blk_off in struct dpu_hw_blk_reg_map").

Fixes: 9403f9a42c88 ("drm/msm/dpu: merge base_off with blk_off in struct dpu_hw_blk_reg_map")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/498736/
Link: https://lore.kernel.org/r/20220822172204.281045-1-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>