DAFS: Do not clear salv state on fssync salvage

DAFS: Do not clear salv state on fssync salvage

When a volume is put into an error state via the FSYNC_VOL_FORCE_ERROR
command, we clear the salvage state informaton on it, since we're
forcing it offline and thus inaccessible. However, if we are forcing
it to an error state because the volume needs salvaging, we just
salvage it. In this case, do not clear the salvage state, since we
need to know if we've already requested or scheduled a salvage so we
can correctly keep track of the number of salvages performed.

Reviewed-on: http://gerrit.openafs.org/4900
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 1ecac71e50e75ce5a45e297d57c480e850975af7)

Change-Id: I313f4c4093f3b4f5ee501ef7537d05b557946a70
Reviewed-on: http://gerrit.openafs.org/4948
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>