[PATCH] libertas: single out mesh code

This patches adds the two functions wlan_add_mesh() and wlan_remove_mesh(),
which are responsible for the mshX interface. In a CF driver with a non-
mesh-aware firmware you can omit the calls to this functions.

Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>