package/lldpd: update license file

package/lldpd: update license file

- Instead of README.md, use LICENSE file that has been added in version
  0.9.5 with
  https://github.com/vincentbernat/lldpd/commit/4d534a60ee33aa2431acb6bfe6d499d2e72d66d5
- Add hash of license file

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Acked-by: Julien Floret <julien.floret@6wind.com
Signed-off-by: Fabrice Fontaine &lt;<a href="mailto:fontaine.fabrice@gmail.com" target="_blank" rel="noreferrer">fontaine.fabrice@gmail.com</a>&gt;<br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>