arm64: dts: qcom: sc7280: Mark FastRPC context banks as dma-coherent

The FastRPC context banks are DMA-coherent on sc7280 platform. Mark them
as such.

This allows LLM inferencing on the CDSP using Qualcomm AI Engine Direct
SDK on the qcs6490 platform.

Signed-off-by: Xilin Wu <sophon@radxa.com>
Link: https://lore.kernel.org/r/20250416-sc7280-fastrpc-dma-v1-1-60ca91116b1e@radxa.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

Author: strongtz

arch/arm64/boot/dts/qcom/sc7280.dtsi

@@ -3906,18 +3906,21 @@
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <3>;
 						iommus = <&apps_smmu 0x1803 0x0>;
+						dma-coherent;
 					};
 
 					compute-cb@4 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <4>;
 						iommus = <&apps_smmu 0x1804 0x0>;
+						dma-coherent;
 					};
 
 					compute-cb@5 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <5>;
 						iommus = <&apps_smmu 0x1805 0x0>;
+						dma-coherent;
 					};
 				};
 			};
@@ -4145,55 +4148,63 @@
 						reg = <1>;
 						iommus = <&apps_smmu 0x11a1 0x0420>,
 							 <&apps_smmu 0x1181 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@2 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <2>;
 						iommus = <&apps_smmu 0x11a2 0x0420>,
 							 <&apps_smmu 0x1182 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@3 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <3>;
 						iommus = <&apps_smmu 0x11a3 0x0420>,
 							 <&apps_smmu 0x1183 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@4 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <4>;
 						iommus = <&apps_smmu 0x11a4 0x0420>,
 							 <&apps_smmu 0x1184 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@5 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <5>;
 						iommus = <&apps_smmu 0x11a5 0x0420>,
 							 <&apps_smmu 0x1185 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@6 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <6>;
 						iommus = <&apps_smmu 0x11a6 0x0420>,
 							 <&apps_smmu 0x1186 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@7 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <7>;
 						iommus = <&apps_smmu 0x11a7 0x0420>,
 							 <&apps_smmu 0x1187 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@8 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <8>;
 						iommus = <&apps_smmu 0x11a8 0x0420>,
 							 <&apps_smmu 0x1188 0x0420>;
+						dma-coherent;
 					};
 
 					/* note: secure cb9 in downstream */
@@ -4203,27 +4214,31 @@
 						reg = <11>;
 						iommus = <&apps_smmu 0x11ab 0x0420>,
 							 <&apps_smmu 0x118b 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@12 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <12>;
 						iommus = <&apps_smmu 0x11ac 0x0420>,
 							 <&apps_smmu 0x118c 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@13 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <13>;
 						iommus = <&apps_smmu 0x11ad 0x0420>,
 							 <&apps_smmu 0x118d 0x0420>;
+						dma-coherent;
 					};
 
 					compute-cb@14 {
 						compatible = "qcom,fastrpc-compute-cb";
 						reg = <14>;
 						iommus = <&apps_smmu 0x11ae 0x0420>,
 							 <&apps_smmu 0x118e 0x0420>;
+						dma-coherent;
 					};
 				};
 			};