Use separate mac80211_ops for rt2800pci and rt2800usb in preparation
for further fixes. This shouldn't introduce functional changes.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>