ixgbe: disable tx engine before disabling tx laser

ixgbe: disable tx engine before disabling tx laser

Disabling the tx laser while receiving DMA requests
can hang the device.  After this occurs the device
is in a bad state. The GPIO bit never clears when
PCI master access is disabled and a reboot is required
to get the device in a good state again.

Signed-off-by: John Fastabend <[email protected]>
Acked-by: Peter P Waskiewicz Jr <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>
Signed-off-by: David S. Miller <[email protected]>