net: Drop IPv4 and IPv6 packet if size is wrong

If the fragment size is different than the value in IP
header, then drop the packet as there is clearly something
wrong in L2 layer. The fragment size must match the value in
protocol headers.

Change-Id: Ibfdb0ab37b3cd4e81e6e03c36beb1e0abfa8c00d
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>