Add support for ethernet IP protocol

Add support for ethernet IP protocol

The SRv6 network programming defines a new IP protocol number [1].

The new protocol number is used in the Next Header field of an IPv6 header
or any extension header indicates that the payload is an Ethernet.

IANA has assigned 143 as the protocol number of ethernet [2].

The SRv6 packet has the following format:
IPv6 HDR + SRH + Ethernet HDR + IPv4/IPv6 packet

This patch allows TCPDUMP to dissect such SRv6 packets.

[1] https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-16#section-9.1
[2] https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml

Signed-off-by: Ahmed Abdelsalam <[email protected]>