nvme: move stopping keep-alive into nvme_uninit_ctrl()

nvme: move stopping keep-alive into nvme_uninit_ctrl()

Commit 4733b65d82bd ("nvme: start keep-alive after admin queue setup")
moves starting keep-alive from nvme_start_ctrl() into
nvme_init_ctrl_finish(), but don't move stopping keep-alive into
nvme_uninit_ctrl(), so keep-alive work can be started and keep pending
after failing to start controller, finally use-after-free is triggered if
nvme host driver is unloaded.

This patch fixes kernel panic when running nvme/004 in case that connection
failure is triggered, by moving stopping keep-alive into nvme_uninit_ctrl().

This way is reasonable because keep-alive is now started in
nvme_init_ctrl_finish().

Fixes: 3af755a46881 ("nvme: move nvme_stop_keep_alive() back to original position")
Cc: Hannes Reinecke <hare@suse.de>
Cc: Mark O'Donovan <shiftee@posteo.net>
Reported-by: Changhui Zhong <czhong@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>