Update the allowed rates before association

This function will set the set of rates allowed for this access point
before the rates are sent to the firmware.

Signed-off-by: Olof Johansson <dev@skyshaper.net>
Enable n-rates

This will enable n-rates on access points with support for n-rates.

Signed-off-by: Olof Johansson <dev@skyshaper.net>