zebra: fix static srv6 segment-list sid order

When configuring a SID list by vtysh, the segment list
obtained in iproute2 is the exact opposite:
>
>vtysh:
>ipv6 route 2005::/64 eth0 segments 2001:db8:aaaa::7/2002::2/2003::3/2004::4
>
>root@r1:/# ip -6 route
>2005::/64 nhid 6  encap seg6 mode encap segs 4 [ 2004::4 2003::3 2002::2 2001:db8:aaaa::7 ] dev dummy0 proto 196 metric 20 pref medium
>

Fix this by keeping the same vtysh config and swap the
segment's order of the list in the rt_netlink.c
>
>root@r1:/# ip -6 route
>2005::/64 nhid 6  encap seg6 mode encap segs 4 [ 2001:db8:aaaa::7 2002::2 2003::3 2004::4 ] dev dummy0 proto 196 metric 20 pref medium
>

Fixes: f20cf14 ("bgpd,lib,sharpd,zebra: srv6 introduce multiple segs/SIDs in nexthop")

Signed-off-by: Dmytro Shytyi <[email protected]>

zebra/rt_netlink.c

@@ -1550,7 +1550,7 @@ static ssize_t fill_seg6ipt_encap(char *buffer, size_t buflen,
 	srh->first_segment = segs->num_segs - 1;
 
 	for (i = 0; i < segs->num_segs; i++) {
-		memcpy(&srh->segments[i], &segs->seg[i],
+		memcpy(&srh->segments[segs->num_segs - i - 1], &segs->seg[i],
 		       sizeof(struct in6_addr));
 	}