ARM: dts: sh73a0: Add missing clocks to sound node

The device node for the FIFO-buffered Serial Interface sound node lacks
the "clocks" property, as the DTS file didn't describe any clocks yet at
its introduction.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200519075525.24742-1-geert+renesas@glider.be

arch/arm/boot/dts/sh73a0.dtsi

@@ -584,6 +584,7 @@ sh_fsi2: sound@ec230000 {
 		compatible = "renesas,fsi2-sh73a0", "renesas,sh_fsi2";
 		reg = <0xec230000 0x400>;
 		interrupts = <GIC_SPI 146 0x4>;
+		clocks = <&mstp3_clks SH73A0_CLK_FSI>;
 		power-domains = <&pd_a4mp>;
 		status = "disabled";
 	};