This patch cleans up several issues with VLANs on igb after the recent
changes that were meant to leave the VLANs enabled/disable via the
netdev->features flags.

Specifically the Rx VLAN settings were being dropped after reset due to the
fact that they were not being restored correctly.  In addition I removed
the IRQ disable/enable since those were in place to protect the setting of
vlgrp.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: NAaron Brown  <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>