This patch removes all mention of the atheros turbo modes that
can't possibly work properly anyway since in some places we don't
check for them when we should.

I have no idea what the iwlwifi drivers were doing with these but
it can't possibly have been correct.

Cc: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>