extract_utils: Fix vendor Android.bp creation with subdirectory

error: vendor/samsung/beyond0lte/Android.bp:37:9: unrecognized property "sub_dir"

Change-Id: I23becda0345f41d2cb1462e74b66a787e9ad4c96
diff --git a/extract_utils.sh b/extract_utils.sh
index 06337d6..7b6e9cc 100644
--- a/extract_utils.sh
+++ b/extract_utils.sh
@@ -458,7 +458,7 @@
         fi
         if [ "$CLASS" = "SHARED_LIBRARIES" ] || [ "$CLASS" = "EXECUTABLES" ] || [ "$CLASS" = "ETC" ] ; then
             if [ "$DIRNAME" != "." ]; then
-                printf '\tsub_dir: "%s",\n' "$DIRNAME"
+                printf '\trelative_install_path: "%s",\n' "$DIRNAME"
             fi
         fi
         if [ "$CLASS" = "SHARED_LIBRARIES" ] || [ "$CLASS" = "EXECUTABLES" ] ; then