fbo: grab lock around FBO_PREV_EJECT use
fbo: grab lock around FBO_PREV_EJECT use

We currently do not use the FBO_PREV_EJECT but assuming we
are going to, this grabs the lock when setting it to prevent
races where 2 ALLOW_MEDIUM_REMOVAL could be executing from
different threads at the same time.

Signed-off-by: Mike Christie <39daeb1549a929782e38aa87c4e3da7f3844b09a@redhat.com>

open-iscsi/tcmu-runner,open-iscsi/tcmu-runner,agrover/tcmu-runner