Change the default BR2_DL_DIR location

Change to default Download dir so that different 'make O=<directory>'
commands will use the same location by default without having to
create a symlink in <directory> or having to export BUILDROOT_DL_DIR.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

Config.in

@@ -69,13 +69,13 @@ config BR2_TAR_OPTIONS
 
 config BR2_DL_DIR
 	string "Download dir"
-	default "$(BASE_DIR)/dl"
+	default "$(TOPDIR)/dl"
 	help
 	  Directory to store all the source files that we need to fetch.
 	  If the Linux shell environment has defined the BUILDROOT_DL_DIR
 	  environment variable, then this overrides this configuration item.
 
-	  The default is $(BASE_DIR)/dl
+	  The default is $(TOPDIR)/dl
 
 config BR2_COPYTO
 	string "Copy result to..."