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: 6d084806 ("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.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c

@@ -270,6 +270,7 @@ static void dpu_hw_ctl_update_pending_flush_wb(struct dpu_hw_ctl *ctx,
 	case WB_1:
 	case WB_2:
 		ctx->pending_flush_mask |= BIT(WB_IDX);
+		break;
 	default:
 		break;
 	}