ether: add IEEE 1722 ethertype - TSN

ether: add IEEE 1722 ethertype - TSN

IEEE 1722 describes AVB (later renamed to TSN - Time Sensitive
Networking), a protocol, encapsualtion and synchronization to utilize
standard networks for audio/video (and later other time-sensitive)
streams.

This standard uses ethertype 0x22F0.

http://standards.ieee.org/develop/regauth/ethertype/eth.txt

This is a respin of a previous patch ("ether: add AVB frame type
ETH_P_AVB")

CC: "David S. Miller" <davem@davemloft.net>
CC: netdev@vger.kernel.org
CC: linux-api@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Henrik Austad <henrik@austad.us>
Signed-off-by: David S. Miller <davem@davemloft.net>