Remove temporary directory after building factory toolkit

This fixes a bug that the temporary directory is left at the output
path after a factory toolkit is built.

BUG=chrome-os-partner:24798
TEST=Build factory toolkit and check temporary directory is deleted.

Change-Id: I907a0efab10b7566eef67ff82c022b5139223a4b
Signed-off-by: Vic (Chun-Ju) Yang <victoryang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/183900
Reviewed-by: Jon Salz <jsalz@chromium.org>
diff --git a/make_factory_toolkit.sh b/make_factory_toolkit.sh
index 1d3a792..e26a3b7 100755
--- a/make_factory_toolkit.sh
+++ b/make_factory_toolkit.sh
@@ -41,7 +41,7 @@
   fi
   cd "${output_dir}"
 
-  local temp_pack_root="$(mktemp -d toolkit_XXXXXX)"
+  temp_pack_root="$(mktemp -d toolkit_XXXXXX)"
   if [[ ! -d "${temp_pack_root}" ]]; then
     die "Failed to create temporary directory."
   fi