imx8mn: Add LPDDR4 EVK board support

Add support for iMX8MN LPDDR4 EVK board which uses 2GB LPDDR4 and
PCA9450B PMIC.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx8m/Kconfig b/arch/arm/mach-imx/imx8m/Kconfig
index 12b8d0d..59a45f7 100644
--- a/arch/arm/mach-imx/imx8m/Kconfig
+++ b/arch/arm/mach-imx/imx8m/Kconfig
@@ -49,6 +49,12 @@
 	select SUPPORT_SPL
 	select IMX8M_LPDDR4
 
+config TARGET_IMX8MN_EVK
+	bool "imx8mn LPDDR4 EVK board"
+	select IMX8MN
+	select SUPPORT_SPL
+	select IMX8M_LPDDR4
+
 config TARGET_IMX8MN_DDR4_EVK
 	bool "imx8mn DDR4 EVK board"
 	select IMX8MN