arm64: dts: renesas: r8a774e1: Add missing audio_clk_b

Add audio_clk_b configured as 0 Hz, this will be overridden by the
boards providing the audio clock.

Fixes: 8183a793 ("arm64: dts: renesas: r8a774e1: Add audio support")
Reported-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20201104105508.21197-1-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/r8a774e1.dtsi

@@ -28,6 +28,12 @@ audio_clk_a: audio_clk_a {
 		clock-frequency = <0>;
 	};
 
+	audio_clk_b: audio_clk_b {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <0>;
+	};
+
 	audio_clk_c: audio_clk_c {
 		compatible = "fixed-clock";
 		#clock-cells = <0>;