arm64: dts: imx8mm-evk: correct pmic clock source

The osc_32k supports #clock-cells as 0, using an id is wrong, drop it.

Fixes: a6a355ed ("arm64: dts: imx8mm-evk: Add 32.768 kHz clock to PMIC")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm-evk.dtsi

@@ -194,7 +194,7 @@ pmic@4b {
 		rohm,reset-snvs-powered;
 
 		#clock-cells = <0>;
-		clocks = <&osc_32k 0>;
+		clocks = <&osc_32k>;
 		clock-output-names = "clk-32k-out";
 
 		regulators {