Unregistering a device should be deferred if I/O
channels still exist. Those I/O channels are likely
undergoing a deferred unregister themselves.
Change-Id: I67186232a58f212b867f6ef894c3d37aae2a4d53
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/370351
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>