warp7: Convert to OF_UPSTREAM

Instead of using the local imx7s-warp devicetree copies from U-Boot,
convert the imx7s-warp board to OF_UPSTREAM so that the upstream
kernel devicetree can be used instead.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/mx7/Kconfig b/arch/arm/mach-imx/mx7/Kconfig
index 3c0208e..2e68557 100644
--- a/arch/arm/mach-imx/mx7/Kconfig
+++ b/arch/arm/mach-imx/mx7/Kconfig
@@ -87,6 +87,7 @@
 	select DM_THERMAL
 	select MX7D
 	imply CMD_DM
+	imply OF_UPSTREAM
 
 config TARGET_COLIBRI_IMX7
 	bool "Support Colibri iMX7S/iMX7D modules"