i40e/base: store CEE DCBX config

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.

Store the CEE TLV status returned by firmware to allow drivers to dump that
for debug purposes.

Signed-off-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>
Tested-by: Huilong Xu <huilongx.xu@intel.com>