ixgbe: Fix led interface for X557 devices

The X557 devices use a different interface to the LED for the port.
This patch reflect that change.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>