drm/msm/dpu: Add handling of LM_6 and LM_7 bits in pending flush mask

MDSS/MDP v12 comes with new bits in flush registers (e.g.
MDP_CTL_0_FLUSH) for Layer Mixer 6 and 7.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/651260/
Link: https://lore.kernel.org/r/20250430-b4-sm8750-display-v5-13-8cab30c3e4df@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Author: krzk

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

@@ -261,6 +261,12 @@ static void dpu_hw_ctl_update_pending_flush_mixer(struct dpu_hw_ctl *ctx,
 	case LM_5:
 		ctx->pending_flush_mask |= BIT(20);
 		break;
+	case LM_6:
+		ctx->pending_flush_mask |= BIT(21);
+		break;
+	case LM_7:
+		ctx->pending_flush_mask |= BIT(27);
+		break;
 	default:
 		break;
 	}