libnetlink: Modify the parser to track first duplicated attributes

libnetlink: Modify the parser to track first duplicated attributes

Modify the parser to keep track of the first of any duplicated attributes,
instead of the last. This is required for VF configuration reporting, where
multiple attributes of the same type are added sequentially.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>