Windows: do not forget cm_SyncOpDone

If cm_SyncOp was called, then cm_SyncOpDone must be called.
By goto out of the loop, the cm_SyncOpDone call was skipped.

Change-Id: I20105ec8708c19eecbf215258ada0779cd705f73
Reviewed-on: http://gerrit.openafs.org/11414
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>