namei: Remove redundant linktable SetLinkCount

namei: Remove redundant linktable SetLinkCount

If we're setting the linktable linkcount to 0, we're about to delete
the whole linktable. So, don't bother setting the link count. Still
make sure we unlock the linktable, as we still have it locked at this
point, from the previous GetLinkCount call.

Change-Id: Ia00c1e14de6b8fcd69d594f0dbdbafa32b066dc5
Reviewed-on: http://gerrit.openafs.org/10195
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: D Brashear <shadow@your-file-system.com>