udoo-neo: Convert to OF_UPSTREAM

Instead of using the local imx6sx-udoo-neo  devicetree copies from U-Boot,
convert the imx6sx-udoo-neo boards to OF_UPSTREAM so that the upstream
kernel devicetrees can be used instead.

Tested on a imx6sx-udoo-neo-full board.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
diff --git a/arch/arm/mach-imx/mx6/Kconfig b/arch/arm/mach-imx/mx6/Kconfig
index 7800553..bee9d5f 100644
--- a/arch/arm/mach-imx/mx6/Kconfig
+++ b/arch/arm/mach-imx/mx6/Kconfig
@@ -636,6 +636,7 @@
 	select DM_THERMAL
 	select SUPPORT_SPL
 	imply CMD_DM
+	imply OF_UPSTREAM
 
 config TARGET_SOFTING_VINING_2000
 	bool "Softing VIN|ING 2000"