tests/net: dhcpv6: Avoid directly accessing address of unaligned struct

Use UNALIGNED_MEMBER_ADDR when getting the address of possibly
unaligned structures members instead of attempting to directly
get the address as an offset.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

Author: aescolar

tests/net/dhcpv6/src/main.c

@@ -109,8 +109,10 @@ static void generate_fake_server_duid(void)
 
 	memset(serverid, 0, sizeof(*serverid));
 
-	UNALIGNED_PUT(htons(DHCPV6_DUID_TYPE_LL), &serverid->duid.type);
-	UNALIGNED_PUT(htons(DHCPV6_HARDWARE_ETHERNET_TYPE), &duid_ll->hw_type);
+	UNALIGNED_PUT(htons(DHCPV6_DUID_TYPE_LL),
+		      UNALIGNED_MEMBER_ADDR(serverid, duid.type));
+	UNALIGNED_PUT(htons(DHCPV6_HARDWARE_ETHERNET_TYPE),
+		      UNALIGNED_MEMBER_ADDR(duid_ll, hw_type));
 	memcpy(duid_ll->ll_addr, fake_mac, sizeof(fake_mac));
 
 	serverid->length = DHCPV6_DUID_LL_HEADER_SIZE + sizeof(fake_mac);