ARM: dts: at91: Map MCLK for wm8731 on at91sam9g20ek

The MCLK of the WM8731 on the AT91SAM9G20-EK board is connected to the
PCK0 output of the SoC and is expected to be set to 12MHz. Previously
this was mapped using pre-common clock API calls in the audio machine
driver but the conversion to the common clock framework broke that so
describe things in the DT instead.

Fixes: ff78a189 ("ARM: at91: remove old at91-specific clock driver")
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20220404102806.581374-2-broonie@kernel.org

arch/arm/boot/dts/at91sam9g20ek_common.dtsi

@@ -219,6 +219,12 @@ i2c-gpio-0 {
 		wm8731: wm8731@1b {
 			compatible = "wm8731";
 			reg = <0x1b>;
+
+			/* PCK0 at 12MHz */
+			clocks = <&pmc PMC_TYPE_SYSTEM 8>;
+			clock-names = "mclk";
+			assigned-clocks = <&pmc PMC_TYPE_SYSTEM 8>;
+			assigned-clock-rates = <12000000>;
 		};
 	};