target/user: Do not set unused fields in tcmu_ops

TCMU sets TRANSPORT_FLAG_PASSTHROUGH, so INQUIRY commands will not be
emulated by LIO but passed up to userspace. Therefore TCMU should not
set these, just like pscsi doesn't.

Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>