dlm: fix missing idr_destroy for recover_idr

Which would leak memory for the idr internals.
Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/lockspace.c

@@ -807,6 +807,7 @@ static int release_lockspace(struct dlm_ls *ls, int force)
 
 	dlm_delete_debug_file(ls);
 
+	idr_destroy(&ls->ls_recover_idr);
 	kfree(ls->ls_recover_buf);
 
 	/*