imx: power-domain: Add fsl,imx8mn-gpc compatible string

The driver is compatible with iMX8MN, add missing compatible string.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Ye Li <ye.li@nxp.com>
Cc: uboot-imx <uboot-imx@nxp.com>

drivers/power/domain/imx8m-power-domain.c

@@ -121,6 +121,7 @@ static int imx8m_power_domain_of_to_plat(struct udevice *dev)
 static const struct udevice_id imx8m_power_domain_ids[] = {
 	{ .compatible = "fsl,imx8mq-gpc" },
 	{ .compatible = "fsl,imx8mm-gpc" },
+	{ .compatible = "fsl,imx8mn-gpc" },
 	{ }
 };