nvmet-auth: update sc_c in host response

The target code should set the sc_c bit in calculating the host response
based on the status of the 'concat' setting, otherwise we'll get an
authentication mismatch for hosts setting that bit correctly.

Fixes: 7e091add ("nvme-auth: update sc_c in host response")
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>