net: atm: remove support for Fujitsu FireStream ATM devices

This driver received nothing but automated fixes (mostly spelling
and compiler warnings) since git era begun. Since it's using
virt_to_bus it's unlikely to be used on any modern platform.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>