drm/msm/dpu: add missing break statement for update_pending_flush_wb()

drm/msm/dpu: add missing break statement for update_pending_flush_wb()

Add missing break statement for dpu_hw_ctl_update_pending_flush_wb().
Otherwise this leads to below build warning.

drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c:273:2:
warning: unannotated fall-through between switch labels
           default:
           ^
drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c:273:2:
note: insert 'break;' to avoid fall-through
           default:
           ^
           break;
1 warning generated.

Fixes: 6d084806c8c1 ("drm/msm/dpu: add changes to support writeback in hw_ctl")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/484337/
Link: https://lore.kernel.org/r/1651469981-21469-1-git-send-email-quic_abhinavk@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>