arm64: imx: imx8mm-beacon: Migrate to OF_UPSTREAM

The imx8mm-beacon boards can migrate to OF_UPSTREAM which also
allows for the removal the device tree files.

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/arch/arm/mach-imx/imx8m/Kconfig b/arch/arm/mach-imx/imx8m/Kconfig
index b59a774..2d6c859 100644
--- a/arch/arm/mach-imx/imx8m/Kconfig
+++ b/arch/arm/mach-imx/imx8m/Kconfig
@@ -277,6 +277,7 @@
 	select FSL_CAAM
 	select ARCH_MISC_INIT
 	select SPL_CRYPTO if SPL
+	imply OF_UPSTREAM
 
 config TARGET_IMX8MN_BEACON
 	bool "imx8mn Beacon Embedded devkit"