ice: Add code to control FW LLDP and DCBX

This patch adds code to start or stop LLDP and DCBX in firmware through
use of ethtool private flags.

Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>