dhcp: Compare DIUD_LL as a network short

The existing comparision triggers the following clang assertion:

    error: result of comparison of constant 50331648 with expression of type
    'u16' (aka 'unsigned short') is always true

Section 9.1 of RFC3315 describes the DUID type field as:
    "A DUID consists of a two-octet type code represented in network byte"

correctly convert the local type to a network short for the comparison.

Type: fix
Change-Id: I7cb048035bd5e06372e29471ae6004ee1b2191b9
Signed-off-by: Tom Jones <thj@freebsd.org>

src/plugins/dhcp/dhcp_api.c

@@ -92,7 +92,7 @@ vl_api_dhcp6_duid_ll_set_t_handler (vl_api_dhcp6_duid_ll_set_t * mp)
   int rv = 0;
 
   duid = (dhcpv6_duid_ll_string_t *) mp->duid_ll;
-  if (duid->duid_type != htonl (DHCPV6_DUID_LL))
+  if (duid->duid_type != htons (DHCPV6_DUID_LL))
     {
       rv = VNET_API_ERROR_INVALID_VALUE;
       goto reply;