nvme-tcp: only evaluate 'tls' option if TLS is selected

We only need to evaluate the 'tls' connect option if TLS is
enabled; otherwise we might be getting a link error.

Fixes: 706add13

 ("nvme: keyring: fix conditional compilation")
Reported-by: kernel test robot <yujie.liu@intel.com>
Closes: https://lore.kernel.org/r/202311140426.0eHrTXBr-lkp@intel.com/


Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>