emacs: fix auto configuration of merlin-favourite-caml-mode
emacs: fix auto configuration of merlin-favourite-caml-mode

dra27/merlin,ocaml/merlin,fxfactorial/merlin,the-lambda-church/merlin,the-lambda-church/merlin,chriskonstad/merlin,neojski/merlin,chriskonstad/merlin,dra27/merlin,neojski/merlin,neojski/merlin,chambart/merlin,chambart/merlin,haselwarter/merlin,ocaml/merlin,neojski/merlin,ocaml/merlin,rgrinberg/merlin,rgrinberg/merlin,the-lambda-church/merlin,haselwarter/merlin,rgrinberg/merlin,dra27/merlin,fxfactorial/merlin,chambart/merlin,haselwarter/merlin,rgrinberg/merlin,fxfactorial/merlin,chambart/merlin,ocaml/merlin,haselwarter/merlin,dra27/merlin,fxfactorial/merlin