zebra: display metric for connected routes

zebra: display metric for connected routes

In a VRR/VRRP setup we can have connected routes with different costs.
So this change eliminates suppressing metric display for connected routes.

Sample output -
root@TORC11:~# vtysh -c "show ipv6 route vrf vrf1"
Codes: K - kernel route, C - connected, S - static, R - RIPng,
       O - OSPFv3, I - IS-IS, B - BGP, N - NHRP, T - Table,
       v - VNC, V - VNC-Direct, A - Babel, D - SHARP, F - PBR,
       > - selected route, * - FIB route

VRF vrf1:
K * ::/0 [255/8192] unreachable (ICMP unreachable), 00:00:36
C * 2001:aa:1::/64 [0/100] is directly connected, vlan1002-v0, 00:00:36
C>* 2001:aa:1::/64 [0/90] is directly connected, vlan1002, 00:00:36

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>