tests: Fix nvme_copy_test python traceback fails

tests: Fix nvme_copy_test python traceback fails

Reworking the `get_ocfs` function to correctly parse the ocfs field.
At the same time refactor `nvme id-ctrl` that extracts the ocfs
field into separate functions. This is in preparation for following
commits that reuse the same functionality.

Furthermore nvme_copy_test fails on devices that do not support any
copy formats. For this to pass we need to declare
`self.host_behavior_data` in any case.

Signed-off-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>