pcmcia ether drivers can't be unloaded

[Stephen Hemminger <shemminger@xxxxxxxx>]

It looks like pcmica modular ether (example orinoco) can never be manually 
unloaded because
module refcount is always 1. This comes from the owner field in the 
pcmcia_driver.owner
being set.

One fix is to not set owner field but then there is a hot plug/module remove
race. But the right fix seems to fix up pcmcia to be a true bus in the driver
model and have the same hotplug as other buses; usb and pci don't have the 
problem.