Bring the three path-related options together

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Config.in

@@ -88,8 +88,6 @@ config BR2_COPYTO
 	  Setting this variable will (eventually) override 
 	  any other copyto configurations in buildroot.
 
-source	"target/device/Config.in.mirrors"
-
 config BR2_STAGING_DIR
 	string "Toolchain and header file location?"
 	default "$(BASE_DIR)/staging"
@@ -103,6 +101,8 @@ config BR2_STAGING_DIR
 	  Most people will leave this set to the default value of
 	  "$(BASE_DIR)/staging".
 
+source	"target/device/Config.in.mirrors"
+
 config BR2_GNU_BUILD_SUFFIX
 	string "GNU build hostname suffix"
 	default "pc-linux-gnu"