LU-5396 lod: (and mdt, mgs) make some symbols static

LU-5396 lod: (and mdt, mgs) make some symbols static

Some functions and variables are only used in their C file, so reduce
their scope. This reduces the code size, and fixes sparse warnings
such as:

   warning: symbol 'proc_lnet_routes' was not declared.
       Should it be static?
   warning: symbol 'proc_lnet_routers' was not declared.
       Should it be static?

Some prototypes were removed from C files and added to the proper
header.

Signed-off-by: Frank Zago <fzago@cray.com>
Change-Id: I48d5e51f6f7de030f332bc99b3be3a06ed5b10e1
Reviewed-on: http://review.whamcloud.com/12223
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>