ipmi:si: Don't block module unload if the BMC is messed up

ipmi:si: Don't block module unload if the BMC is messed up

If the BMC is in a bad state, don't bother waiting for queues messages
since there can't be any.  Otherwise the unload is blocked until the
BMC is back in a good state.

Reported-by: Rafael J. Wysocki <rafael@kernel.org>
Fixes: bc3a9d217755 ("ipmi:si: Gracefully handle if the BMC is non-functional")
Cc: stable@vger.kernel.org # 4.18
Signed-off-by: Corey Minyard <corey@minyard.net>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>