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/board/freescale/imx8mn_evk/Kconfig b/board/freescale/imx8mn_evk/Kconfig
index 048fb7d..ace6fc1 100644
--- a/board/freescale/imx8mn_evk/Kconfig
+++ b/board/freescale/imx8mn_evk/Kconfig
@@ -1,4 +1,4 @@
-if TARGET_IMX8MN_DDR4_EVK
+if TARGET_IMX8MN_EVK || TARGET_IMX8MN_DDR4_EVK
 
 config SYS_BOARD
 	default "imx8mn_evk"