ARM: dts: renesas: Switch to using upstream DT

Enable OF_UPSTREAM to use upstream DT and add renesas/ prefix to the
DEFAULT_DEVICE_TREE and OF_LIST. And thereby directly build DTB from
dts/upstream/src/ including *-u-boot.dtsi files from arch/$(ARCH)/dts/
directory.

The configuration update has been done using the following script:
```
sed -i '/^CONFIG_DEFAULT_DEVICE_TREE/ s@="@&renesas/@' `git grep -li renesas configs`
sed -i '/^CONFIG_OF_LIST/ s@r8a@renesas/&@g' `git grep -li renesas configs`
```

The RZN1 Snarc board does not seem to have a matching Linux kernel
DT counterpart, this is currently not switched to OF upstream.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 23ee252..be8ab0f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1068,6 +1068,7 @@
 	imply BOARD_EARLY_INIT_F
 	imply CMD_DM
 	imply FAT_WRITE
+	imply OF_UPSTREAM
 	imply SYS_THUMB_BUILD
 	imply ARCH_MISC_INIT if DISPLAY_CPUINFO