Windows: Set Symlink mpDV after reading target string

Windows: Set Symlink mpDV after reading target string

When a cm_scache object, symlink, has its mountPointString field
successfully populated by cm_GetData(), the mpDV field must be
assigned the current dataVersion value in order to prevent unnecessary
queries of the mountPointString from the file server.

Change-Id: I62b2341459c680d531fd9f4de64dfcc87801ec3e
Reviewed-on: http://gerrit.openafs.org/8762
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>