rt2x00: Use ieee80211 fc handlers

With the introduction of the ieee80211 fc handlers
we can now remove the rt2x00.h versions to use the
global versions.

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