nvmet: fix uninitialized work for zero kato

nvmet: fix uninitialized work for zero kato

When connecting a controller with a zero kato value using the following
command line

   nvme connect -t tcp -n NQN -a ADDR -s PORT --keep-alive-tmo=0

the warning below can be reproduced:

WARNING: CPU: 1 PID: 241 at kernel/workqueue.c:1627 __queue_delayed_work+0x6d/0x90
with trace:
  mod_delayed_work_on+0x59/0x90
  nvmet_update_cc+0xee/0x100 [nvmet]
  nvmet_execute_prop_set+0x72/0x80 [nvmet]
  nvmet_tcp_try_recv_pdu+0x2f7/0x770 [nvmet_tcp]
  nvmet_tcp_io_work+0x63f/0xb2d [nvmet_tcp]
  ...

This is caused by queuing up an uninitialized work.  Althrough the
keep-alive timer is disabled during allocating the controller (fixed in
43d3947a66f5), ka_work still has a chance to run (called by
nvmet_start_ctrl).

Fixes: 43d3947a66f5 ("nvmet: Disable keep-alive timer when kato is cleared to 0h")
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>