ospf6d: fix NSSA area-range command
When an area-range command is applied in an ABR, the more specific prefixes
need to be removed.
r2# sh ipv6 ospf database
AS Scoped Link State Database
Type LSId AdvRouter Age SeqNum Payload
ASE 0.0.0.1 10.254.254.2 53
80000001 ::
ASE 0.0.0.2 10.254.254.2 51
80000001 2001:db8:1::/64
ASE 0.0.0.3 10.254.254.2 51
80000001 2001:db8:3::/64
ASE 0.0.0.4 10.254.254.2 51
80000001 2001:db8:2::/64
ASE 0.0.0.5 10.254.254.2 46
80000001 2001:db8:1::/64
ASE 0.0.0.6 10.254.254.2 46
80000001 2001:db8:3::/64
ASE 0.0.0.7 10.254.254.2 46
80000001 2001:db8:2::/64
ASE 0.0.0.8 10.254.254.2 41
80000001 2001:db8:3::/64
ASE 0.0.0.9 10.254.254.2 41
80000001 2001:db8:1000::1/128 <-- **
ASE 0.0.0.10 10.254.254.2 41
80000001 2001:db8:1000::2/128 <-- **
ASE 0.0.0.12 10.254.254.2 24
80000001 2001:db8:1000::/64
ASE 0.0.0.1 10.254.254.3 52
80000001 2001:db8:2::/64
Signed-off-by: ckishimo <carles.kishimoto@gmail.com>