arm: dts: imx8mp-beacon-kit: Resync DTS with Linux 6.8

The device tree has evolved over time, so re-sync.  This also
partial reverts one change on the PCIe, because U-Boot doesn't
have a proper driver.  However, since the clock is configured
to generate a 100MHz reference clock by default, a proper driver
isn't really necessary.

Signed-off-by: Adam Ford <aford173@gmail.com>
Acked-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/dts/imx8mp-beacon-kit-u-boot.dtsi b/arch/arm/dts/imx8mp-beacon-kit-u-boot.dtsi
index 393fd8e..ed183f8 100644
--- a/arch/arm/dts/imx8mp-beacon-kit-u-boot.dtsi
+++ b/arch/arm/dts/imx8mp-beacon-kit-u-boot.dtsi
@@ -6,6 +6,13 @@
 #include "imx8mp-u-boot.dtsi"
 
 / {
+	/* U-Boot does not yet have a proper PCIe clk driver */
+	pcie0_refclk: clock-pcie {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <100000000>;
+	};
+
 	wdt-reboot {
 		compatible = "wdt-reboot";
 		wdt = <&wdog1>;
@@ -13,6 +20,10 @@
 	};
 };
 
+&pcie_phy {
+	clocks = <&pcie0_refclk>;
+};
+
 &{/soc@0/bus@30800000/i2c@30a20000/pmic@25} {
 	bootph-pre-ram;
 };