mac80211: configure 11b/g channel access rules for legacy APs

For each EDCA TX queue change default settings (in STA mode) to conform
old 802.11b/g channel access rules. This is needed for drivers that do
not have QoS enable/disable "switch" (like rt2x00) to make them work
properly with legacy APs.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>