package/frr: drop libnl dependency
libnl is not needed to build frr since the addition of the package in
commit 26d82d006ba15777d19892b327bde343d82a9ff5
No mention of libnl found in https://github.com/FRRouting/frr or
https://docs.frrouting.org/projects/dev-guide/en/latest/building.html
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit efa955ac415e2b50f63710e4fc1de8fd3e0dc099)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>