ixgbe: fix possible race in reset subtask

Similar to ixgbevf, the same possibility for race exists. Extend the RTNL
lock in ixgbe_reset_subtask() to protect the state bits; this is to make
sure that we get the most up-to-date values for the bits and avoid a
possible race when going down.

Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>