nvme/{033,034,035,036,37}: drop port handle between passthru target setup and cleanup

nvme/{033,034,035,036,37}: drop port handle between passthru target setup and cleanup

The passthru nvmet setup and cleanup helpers are using the port as
handle to track resources.

Instead returning the port from the setup call, we figure out in the
cleanup code which resources have been allocated. This avoids passing
around awkward handles.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>