Windows: cm_UpdateIFInfo consolidate syscfg_GetIFInfo calls

Add a new function cm_UpdateIFInfo() that consolidates all of the
syscfg_GetIFInfo() call functionality into a single rountine.  Replace
all of the existing call sites.

It is safe to call cm_UpdateIFInfo() without holding cm_syscfgLock
during afsd initialization because no other threads have been created.

Reviewed-on: http://gerrit.openafs.org/11443
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 95c3db9c7ccb86c7ad384c06094c066107de262c)

Change-Id: I69bb6721902deff326442e422c3375618b4d6ca3
Reviewed-on: http://gerrit.openafs.org/11494
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>