arm64: dts: qcom: sc7280: Mark Adreno SMMU as DMA coherent

The SMMUs on sc7280 are cache-coherent. APPS_SMMU is marked as such,
mark the GPU one as well.

Fixes: 96c47197 ("arm64: dts: qcom: sc7280: Add gpu support")
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20230926-topic-a643-v2-3-06fa3d899c0a@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>

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

@@ -2788,6 +2788,7 @@ adreno_smmu: iommu@3da0000 {
 					"gpu_cc_hub_aon_clk";
 
 			power-domains = <&gpucc GPU_CC_CX_GDSC>;
+			dma-coherent;
 		};
 
 		remoteproc_mpss: remoteproc@4080000 {