i40e/i40evf: Store CEE DCBX DesiredCfg and RemoteCfg

This patch adds capability to query and store the CEE DCBX DesiredCfg
and RemoteCfg data from the LLDP MIB.
Added new member "desired_dcbx_config" in the i40e_hw data structure
to hold CEE only DesiredCfg data.

Change-ID: I19c550369594384eaff4cc63e690ca740231195d
Signed-off-by: Neerav Parikh <neerav.parikh@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>