emacs-lisp: Fix mode hook
emacs-lisp: Fix mode hook

Fix incorrect use of spacemacs/add-to-hook which used emacs-lisp-mode
for the hook variable. Since we are only adding a single function to the
hook, just use add-hook.

tsonntag/dotemacs,tsonntag/dotemacs,tsonntag/dotemacs,tsonntag/dotemacs