bgpd: store "no neighbor activate" for IPv4 unicast

bgpd: store "no neighbor activate" for IPv4 unicast

If a neighbor was in a peer group for any AFI/SAFI, bgpd would never write a
"no neighbor activate" line for IPv4 unicast, so a valid setup like following
could be configured, but not saved:

    router bgp 64600
     bgp router-id 198.51.100.1
     network 198.51.100.0/24
     neighbor peers peer-group
     neighbor 2001:db8::2 remote-as 64601
     no neighbor 2001:db8::2 activate
    !
     address-family ipv6
     network 2001:db8:1::/48
     neighbor peers activate
     neighbor peers soft-reconfiguration inbound
     neighbor 2001:db8::2 peer-group peers
     exit-address-family
    !

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>