As the code is designed for re-entrant calls from raven_io_ops to
pci-conf, mark raven_io_ops as reentrancy-safe.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20230427211013.2994127-8-alxndr@bu.edu>
Signed-off-by: Thomas Huth <thuth@redhat.com>