igb: Fixes needed for surprise removal support

This patch adds some checks in order to prevent panic's on surprise
removal of devices during S0, S3, S4.  Without this patch, Thunderbolt
type device removal will panic the system.

Signed-off-by: Yanir Lubetkin <yanirx.lubetkin@intel.com>
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>