emacs-lisp: add missing '\' in template

emacs-lisp: add missing '\' in template

Fixes the generated setup_message_id_table(...)
implementation. Without a level of quoting in the emacs lisp skeleton,
the underscore macro used to generate calls to
vl_msg_api_add_msg_name_crc produces "fooCRC" instead of "foo_CRC".
That confuses the Python language binding.

Punctuation saves lives: "Let's eat Grandma" vs. "Let's eat, Grandma."
Or some such.

Change-Id: Ibecc20337092199d6757165ac96b70c830511bb3
Signed-off-by: Dave Barach <[email protected]>