libnetutil: Check dhcp respose packet length am: 61f25d4a36 am: cee6d38c55 am: 29d054046f am: c29049f4f8 am: 3de04e9840 am: 19702dc499
am: 8191e9ba87

Change-Id: Ia297a2af179285b63e7d5d3d1d64baf71dadaef0