ixgbe: Disable flow control for XFI

Flow control autonegotiation is not supported for XFI.  Make sure that
ixgbe_device_supports_autoneg_fc() returns false and
hw->fc.disable_fc_autoneg is set to true to avoid running the fc_autoneg
function for that device.

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