ixgbe: DCB, PFC not cleared until reset occurs

The PFC configuration is not cleared until the device is reset. This
has not been a problem because setting DCB attributes forced a
hardware reset. Now that we no longer require this reset to occur
PFC remains configured even after being disabled until the
device is reset.

This removes a goto in the PFC hardware set routines for 82598 and
82599 devices that was short circuiting the clear.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>