i40e: Allow disabling FW LLDP on X722 devices

This patch allows disabling FW LLDP agent on X722 devices.
It also changes a source of information for this feature from
pf->hw_features to pf->hw.flags which are set in i40e_init_adminq.

Signed-off-by: Patryk Małek <patryk.malek@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>