MFC r214894:

MFC r214894:
Instead of using the AMRR ratectl algo as default for drivers which have
the IEEE80211_C_RATECTL flag set, default to NONE for all drivers. Only if
a driver calls ieee80211_ratectl_init() check if the NONE algo is still
selected and try to use AMRR in that case. Drivers are still free to use
any other algo by calling ieee80211_ratectl_set() prior to the
ieee80211_ratectl_init() call.

After this change it is now safe to assume that a ratectl algo is always
available and selected, which renders the IEEE80211_C_RATECTL flag pretty
much useless. Therefore revert r211314 and 211546.

git-svn-id: svn://svn.freebsd.org/base/stable/8@215557 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f