igb: SR-IOV init reordering

igb is ineffective at setting a lower total VFs because:

int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
{
        ...
        /* Shouldn't change if VFs already enabled */
        if (dev->sriov->ctrl & PCI_SRIOV_CTRL_VFE)
                return -EBUSY;

Swap init ordering.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>