IEEE802.1q Packet returns incorrect header size

IEEE8021Q class uses the Packet.getHeaderSize() which iterates through
header fields to determine the size. .1Q header is fixed in size and
should return the correct value

Change-Id: I4b0123dd943f6e833f14782f2ed7cc0e6e184e87
Signed-off-by: Yevgeny Khodorkovsky <ykhodork@cisco.com>
Merge "IEEE802.1q Packet returns incorrect header size"