arm64: dts: qcom: sa8775p: add the SGMII PHY node

Add the internal SGMII/SerDes PHY node for sa8775p platforms.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Tested-by: Andrew Halaney <ahalaney@redhat.com>
Link: https://lore.kernel.org/r/20230622120142.218055-2-brgl@bgdev.plSigned-off-by: Bjorn Andersson <andersson@kernel.org>

arch/arm64/boot/dts/qcom/sa8775p.dtsi

@@ -1837,6 +1837,15 @@ adreno_smmu: iommu@3da0000 {
 				     <GIC_SPI 687 IRQ_TYPE_LEVEL_HIGH>;
 		};
 
+		serdes0: phy@8901000 {
+			compatible = "qcom,sa8775p-dwmac-sgmii-phy";
+			reg = <0x0 0x08901000 0x0 0xe10>;
+			clocks = <&gcc GCC_SGMI_CLKREF_EN>;
+			clock-names = "sgmi_ref";
+			#phy-cells = <0>;
+			status = "disabled";
+		};
+
 		pdc: interrupt-controller@b220000 {
 			compatible = "qcom,sa8775p-pdc", "qcom,pdc";
 			reg = <0x0 0x0b220000 0x0 0x30000>,