rt2x00: Enable master and adhoc mode again

This will enable the creation of master mode and adhoc
interfaces again. This does not mean the issues surrounding
beaconing have been resolved, but this will make testing
easier and perhaps we can discover which cards are actually
working and which ones not.

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