[netdrvr] skfp: remove a bunch of dead code

The driver has not compiled in anything except PCI support for many
years (see drivers/net/skfp/Makefile).  This driver is also unmaintained
for many years, so arguments for keeping the cross-OS, cross-bus (ISA,
EISA, MCA) code do not exist.

Signed-off-by: Jeff Garzik <jeff@garzik.org>