arm64: dts: verdin-imx8mm: fix dahlia audio playback

Set optional `simple-audio-card,mclk-fs` parameter to ensure a proper
clock to the wm8904 audio codec. Without this change with an audio
stream rate of 44.1 kHz the playback is completely distorted.

Fixes: 6a57f224f734 ("arm64: dts: freescale: add initial support for verdin imx8m mini")
Signed-off-by: Emanuele Ghidoli <[e-mail]>
Signed-off-by: Francesco Dolcini <[e-mail]>
Reviewed-by: Fabio Estevam <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

arch/arm64/boot/dts/freescale/imx8mm-verdin-dahlia.dtsi

···
 		simple-audio-card,bitclock-master = <&dailink_master>;
 		simple-audio-card,format = "i2s";
 		simple-audio-card,frame-master = <&dailink_master>;
+		simple-audio-card,mclk-fs = <256>;
 		simple-audio-card,name = "imx8mm-wm8904";
 		simple-audio-card,routing =
 			"Headphone Jack", "HPOUTL",