bozo: remove obsolete bnode_Deactivate() prototype

Commit 54eb2485b59550ba42569ed3a8d76211a3a35019 removed the
implementation of bnode_Deactivate(), which had been #ifdef'd out
for a long time, but left the prototype in place. Remove the
obsolete declaration in bosprototypes.h as well.

Reviewed-on: http://gerrit.openafs.org/10868
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Perry Ruiter <pruiter@sinenomine.net>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 01a7c64e472c241798306e7f8137de28efdef37e)

Change-Id: Ic1ca95ef455705a14cf68f0801d73789cc7bd4b5
Reviewed-on: http://gerrit.openafs.org/11192
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>