Revert "igb: Fix a deadlock in igb_sriov_reinit"

This reverts commit 3eb14ea8 ("igb: Fix a deadlock in
igb_sriov_reinit")
It is the same as commit f468adc9

 ("igb: missing rtnl_unlock in
igb_sriov_reinit()")
There is no rtnl_lock() in igb_resume before, rtnl_unlock will cause a
deadlock.

Signed-off-by: Arika Chen <arika.chen@huawei.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>