MIPS: add initial infrastructure for device-tree files

Prepare sub-folder for device-tree files. Make support for
device-tree on MIPS available in Kbuild/Kconfig.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
diff --git a/arch/Kconfig b/arch/Kconfig
index 1709d40..ec12013 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -55,6 +55,7 @@
 	select HAVE_PRIVATE_LIBGCC
 	select HAVE_GENERIC_BOARD
 	select SYS_GENERIC_BOARD
+	select SUPPORT_OF_CONTROL
 
 config NDS32
 	bool "NDS32 architecture"