nvme: use helper nvme_ctrl_state in nvme_keep_alive_finish function
We no more need acquiring ctrl->lock before accessing the
NVMe controller state and instead we can now use the helper
nvme_ctrl_state. So replace the use of ctrl->lock from
nvme_keep_alive_finish function with nvme_ctrl_state call.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> Signed-off-by: Keith Busch <kbusch@kernel.org>