salvager: Do not break cbks when salvaging parts

salvager: Do not break cbks when salvaging parts

When salvaging whole partitions / whole servers, the fileserver is
assumed to not be running. So only break callbacks if we are salvaging
a single volume. If we are salvaging a whole partition, do not tell
the fileserver to break callbacks on changed volumes, since the
fileserver will not be around and we will just hang.

Reviewed-on: http://gerrit.openafs.org/2865
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit fabd590cc4b0142fe97c4ffa6a4669fe5d44c359)

Change-Id: I62eaa14c95ecce3dcd5fdde97f3a45f9103fc7bc
Reviewed-on: http://gerrit.openafs.org/4175
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>