i40e: Add capability flag for stopping FW LLDP

Add HW capability flag to indicate that firmware supports stopping
LLDP agent. This feature has been added in FW API 1.7 for XL710
devices and 1.6 for X722. Also raise expected minor version number
for X722 FW API to 6.

Signed-off-by: Krzysztof Galazka <krzysztof.galazka@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>