arm64: dts: imx8mq-librem5: describe the clock for the csi sensors

The CLKO2 clock is used for both camera CSI interfaces as the
driving clock for the connected sensors. In order for it to be
available, use this hog. We can't simply add it to 2 different
sensor descriptions.
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

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

@@ -371,6 +371,16 @@ pmic-5v-hog {
 };
 
 &iomuxc {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_hog>;
+
+	pinctrl_hog: hoggrp {
+		fsl,pins = <
+			/* CLKO2 for cameras on both CSI1 and CSI2 */
+			MX8MQ_IOMUXC_GPIO1_IO15_CCMSRCGPCMIX_CLKO2      0x1f
+		>;
+	};
+
 	pinctrl_audiopwr: audiopwrgrp {
 		fsl,pins = <
 			/* AUDIO_POWER_EN_3V3 */