arm64: dts: qcom: sa8155p-adp: Disable multiple Tx and Rx queues for ethernet IP

Fix the issues seen with ethernet traffic getting stalled on SA8155p-ADP
board with default (or larger) mtu size of 1500 bytes, by disabling
multiple Tx and Rx queues for the stmmac IP block.

With the single queue setup, the ethernet traffic is stable,
wget / curl can work well on the board and no ethernet stall is
observed even when longer netperf / iperf3 test are run. Also
a performance of ~940 Mbits/sec is observed on the 1G link, so
there is no observable degradation in performance as well.

Fixes: c5cb42cc ("arm64: dts: qcom: sa8155p-adp: Enable ethernet node")
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220423195003.353150-1-bhupesh.sharma@linaro.org

arch/arm64/boot/dts/qcom/sa8155p-adp.dts

@@ -49,7 +49,7 @@ vreg_s4a_1p8: smps4 {
 	};
 
 	mtl_rx_setup: rx-queues-config {
-		snps,rx-queues-to-use = <4>;
+		snps,rx-queues-to-use = <1>;
 		snps,rx-sched-sp;
 
 		queue0 {
@@ -58,28 +58,10 @@ queue0 {
 			snps,route-up;
 			snps,priority = <0x1>;
 		};
-
-		queue1 {
-			snps,dcb-algorithm;
-			snps,map-to-dma-channel = <0x1>;
-			snps,route-ptp;
-		};
-
-		queue2 {
-			snps,avb-algorithm;
-			snps,map-to-dma-channel = <0x2>;
-			snps,route-avcp;
-		};
-
-		queue3 {
-			snps,avb-algorithm;
-			snps,map-to-dma-channel = <0x3>;
-			snps,priority = <0xC>;
-		};
 	};
 
 	mtl_tx_setup: tx-queues-config {
-		snps,tx-queues-to-use = <4>;
+		snps,tx-queues-to-use = <1>;
 		snps,tx-sched-wrr;
 
 		queue0 {
@@ -87,24 +69,6 @@ queue0 {
 			snps,dcb-algorithm;
 			snps,priority = <0x0>;
 		};
-
-		queue1 {
-			snps,weight = <0x11>;
-			snps,dcb-algorithm;
-			snps,priority = <0x1>;
-		};
-
-		queue2 {
-			snps,weight = <0x12>;
-			snps,dcb-algorithm;
-			snps,priority = <0x2>;
-		};
-
-		queue3 {
-			snps,weight = <0x13>;
-			snps,dcb-algorithm;
-			snps,priority = <0x3>;
-		};
 	};
 };