Fix locking in FlushVCBs when called from discon

The disconnected code doesn't request locking from FlushVCBs when
it calls it, but also doesn't hold the required locks itself.

Fix this.

Change-Id: I2450df4b19b2d44dca80990197e5e7637c9c8334
Reviewed-on: http://gerrit.openafs.org/802
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>

src/afs/afs_vcache.c

@@ -3265,11 +3265,10 @@ afs_DisconGiveUpCallbacks(void) {
             }
         }
     }
-    /*printf("%d callbacks to be discarded. queued ... ", nq);*/
-    afs_FlushVCBs(0);
-    
+
     ReleaseWriteLock(&afs_xvcache);
-    /*printf("gone\n");*/
+
+    afs_FlushVCBs(1);
 }
 
 /*!