ARM: shmobile: r8a7790: Add default PCIe bus clock

This patch adds a default PCIe bus clock node.
Signed-off-by: NPhil Edworthy <phil.edworthy@renesas.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7790.dtsi

@@ -487,6 +487,15 @@
 			clock-output-names = "extal";
 		};
 
+		/* External PCIe clock - can be overridden by the board */
+		pcie_bus_clk: pcie_bus_clk {
+			compatible = "fixed-clock";
+			#clock-cells = <0>;
+			clock-frequency = <100000000>;
+			clock-output-names = "pcie_bus";
+			status = "disabled";
+		};
+
 		/*
 		 * The external audio clocks are configured as 0 Hz fixed frequency clocks by
 		 * default. Boards that provide audio clocks should override them.