arm64: imx: imx8mp-debix-model-a: Migrate to OF_UPSTREAM

Device tree for this board can be deleted. Device tree location
now points to the freescale/ directory.

Use absolute path to PMIC node entry and its regulators as
device tree in kernel does not provide corresponding labels

Signed-off-by: Gilles Talis <gilles.talis@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx8m/Kconfig b/arch/arm/mach-imx/imx8m/Kconfig
index d1fdaec..9d1fabe 100644
--- a/arch/arm/mach-imx/imx8m/Kconfig
+++ b/arch/arm/mach-imx/imx8m/Kconfig
@@ -197,6 +197,7 @@
 	select IMX8MP
 	select IMX8M_LPDDR4
 	select SUPPORT_SPL
+	imply OF_UPSTREAM
 
 config TARGET_IMX8MP_DH_DHCOM_PDK2
 	bool "DH electronics DHCOM Premium Developer Kit (2) i.MX8M Plus"