diff-hl-stage-some: Ensure it works with diff-hl-update-async on

By disabling async inside it.

Author: dgutov

diff-hl.el

@@ -922,6 +922,7 @@ Pops up a diff buffer that can be edited to choose the changes to stage."
          (file buffer-file-name)
          (dest-buffer (get-buffer-create "*diff-hl-stage-some*"))
          (orig-buffer (current-buffer))
+         (diff-hl-update-async nil)
          ;; FIXME: If the file name has double quotes, these need to be quoted.
          (file-base (file-name-nondirectory file)))
     (with-current-buffer dest-buffer