ocfs2/dlm: clean up deadcode in dlm_master_request_handler()

When 'dispatch_assert' is set, 'response' must be DLM_MASTER_RESP_YES,
and 'res' won't be null, so execution can't reach these two branch.

Link: http://lkml.kernel.org/r/58174C91.3040004@huawei.com
Signed-off-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Joseph Qi Joseph Qi <jiangqi903@gmail.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>