overlays: allo-katana-dac-audio: Reduce I2C clock

Higher speeds have been shown to cause data corruption on a Pi 4,
possibly due to clock-stretching.

See: #5511

Signed-off-by: Phil Elwell <[email protected]>

Author: pelwell

arch/arm/boot/dts/overlays/allo-katana-dac-audio-overlay.dts

@@ -30,6 +30,7 @@
 			#address-cells = <1>;
 			#size-cells = <0>;
 			status = "okay";
+			clock-frequency = <50000>;
 
 			allo-katana-codec@30 {
 				#sound-dai-cells = <0>;