Remove the if_ze and if_zp drivers.

Remove the if_ze and if_zp drivers.

These drivers were cloned from the ed and ep drivers back in 1994
when PCMCIA cards were a very new thing and we had no other support
for such devices.  They treated the PCIC (the chip which controls the
PCCARD slot) as part of their device and generally hacked their way
to success.  They have significantly bit-rotted relative to their
ancestor drivers (ed & ep) and they were a dead-end on the evolution
path to proper PCCARD support in FreeBSD.

They have been terminally broken since August 18 where mdodd forgot
them and nobody seems to have missed them enough to fix them since.

I found no outstanding PRs against these drivers.