Neighbour advertisements dont have hop limit field

Unsolicited neighbour advertisement hop limit was accidently filled.
Neighbour advertisements do not have this field and filling this field
set some flags accidently in the neighbour advertisement packet.

Signed-off-by: Guvenc Gulce <guevenc.guelce@sap.com>

src/dp_periodic_msg.c

@@ -156,7 +156,6 @@ void trigger_nd_unsol_adv(void)
 	icmp6_hdr->icmp6_solicited = 0;
 	icmp6_hdr->icmp6_override = 1;
 	icmp6_hdr->icmp6_router = 1;
-	icmp6_hdr->icmp6_hop_limit = 255;
 
 	DP_ARRAY_FROM_IPV6(ns_msg->target, gw_ip);
 	pkt_size = sizeof(struct rte_ether_hdr) + sizeof(struct rte_ipv6_hdr) +