Implement latest changed from mac80211 configuration
handling to optmize configuration handling in rt2x00.
* Remove set_retry_limit callback function, handled
through config()
* Move config_antenna to its own callback function,
it isn't handled by mac80211 anymore
* Use IEEE80211_CONF_CHANGED_* flags and remove manual
checks
* Removed deprecated short slot setting through config()
and put it in config_erp() through which mac80211 now
configures it
* Remove config_phymode() and move contents to config_erp()
since it only managed the basic rates which is now
determined by mac80211 through config_erp().
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>