bgpd: Actually display labeled unicast routes received

bgpd: Actually display labeled unicast routes received

The labeled unicast and unicast tables have been combined
into the unicast table.  Additionally we have a restriction
where if you configure labeled unicast you cannot configure
unicast.  This created a bug with 'show bgp ipv4 labeled-unicast summ'
command where we were displaying NoNeg, because v4 has been intentionally
turned off.

Modify the code so that when we are looking up if we have negotiated
a capapbility we use the correct one, while still using the appropriate
table for prefix count.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>