arm64: dts: imx8mq-librem5-devkit: Add missing clock-cells to PMIC

The PMIC node can be a clock provider (for its 32 kHz clock) and authors
of imx8mq-librem5-devkit.dts apparently wanted this because they added
input clock and clock-output-names.

Add necessary clock-cells to the PMIC node.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-and-tested-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts

@@ -285,6 +285,7 @@
 		pinctrl-0 = <&pinctrl_pmic>;
 		clocks = <&pmic_osc>;
 		clock-names = "osc";
+		#clock-cells = <0>;
 		clock-output-names = "pmic_clk";
 		interrupt-parent = <&gpio1>;
 		interrupts = <3 GPIO_ACTIVE_LOW>;