imx: imx8mp_evk: convert to OF_UPSTREAM

Convert to OF_UPSTREAM for i.MX8MP EVK

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 cb8afce..fbde476 100644
--- a/arch/arm/mach-imx/imx8m/Kconfig
+++ b/arch/arm/mach-imx/imx8m/Kconfig
@@ -222,6 +222,7 @@
 	select FSL_CAAM
 	select ARCH_MISC_INIT
 	select SPL_CRYPTO if SPL
+	imply OF_UPSTREAM
 
 config TARGET_IMX8MP_VENICE
 	bool "Support Gateworks Venice iMX8M Plus module"