Remove undocumented and rather old "ether proto" protocols

Remove undocumented and rather old "ether proto" protocols

They were never documented (at least since version 0.4 - 1999).

The only documented protocols are:
    ether proto protocol
          True if the packet is of ether type protocol.  Protocol can be a
          number  or  one  of the names aarp, arp, atalk, decnet, ip, ip6,
          ipx, iso, lat, mopdl, moprc, netbeui, rarp, sca  or  stp.
(pcap-filter man page)

They are rather old and unlikely to be found in a capture file.

Summary:

protocol	value	IANA ieee-802-numbers.xhtml
--------        -----   ---------------------------
decdns		803c	DEC Unassigned
decdts		803e	DEC Unassigned
lanbridge	8038	DEC LANBridge
pup		0200	XEROX PUP
sprite		0500	<Unkwown in IANA Registry>
vexp		805b	Stanford V Kernel exp.
vprod		805c	Stanford V Kernel prod.
xns		0600	XEROX NS IDP