afs_vcache: remove redundant assignment in afs_FlushAllVCaches()

Don't do in the body of the loop that which the loop itself
already does.

Change-Id: I41b5cbee86ab783d59024d8961c933525a5128d7
Reviewed-on: http://gerrit.openafs.org/7780
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>

src/afs/afs_vcache.c

@@ -852,7 +852,6 @@ afs_FlushAllVCaches(void)
 	    if (slept) {
 		goto retry;
 	    }
-	    tvc = nvc;
 	}
     }