Kconfig: Create a new tools menu

At present MKIMAGE_DTC_PATH is in the devicetree menu but not within
'devicetree control' since it does not relate to that. As a result it
shows up in the top menu.

It actually relates to the mkimage tool, so create a new tools menu for it
and move it there.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Kconfig b/Kconfig
index c385535..520679f 100644
--- a/Kconfig
+++ b/Kconfig
@@ -453,3 +453,5 @@
 source "lib/Kconfig"
 
 source "test/Kconfig"
+
+source "tools/Kconfig"
diff --git a/dts/Kconfig b/dts/Kconfig
index 046a54a..86ea8ce 100644
--- a/dts/Kconfig
+++ b/dts/Kconfig
@@ -377,12 +377,3 @@
 	  declarations for each node. See of-plat.txt for more information.
 
 endmenu
-
-config MKIMAGE_DTC_PATH
-	string "Path to dtc binary for use within mkimage"
-	default "dtc"
-	help
-	  The mkimage host tool will, in order to generate FIT images make
-	  calls to the dtc application in order to create the output.  In
-	  some cases the system dtc may not support all required features
-	  and the path to a different version should be given here.
diff --git a/tools/Kconfig b/tools/Kconfig
new file mode 100644
index 0000000..b2f5012
--- /dev/null
+++ b/tools/Kconfig
@@ -0,0 +1,12 @@
+menu "Tools options"
+
+config MKIMAGE_DTC_PATH
+	string "Path to dtc binary for use within mkimage"
+	default "dtc"
+	help
+	  The mkimage host tool will, in order to generate FIT images make
+	  calls to the dtc application in order to create the output.  In
+	  some cases the system dtc may not support all required features
+	  and the path to a different version should be given here.
+
+endmenu