AP: add station with basic rates configuration

AP: add station with basic rates configuration

When a new station is added, let it have some supported rates
(they're empty without this change), using the basic rates
that it must support to connect.

This, together with the kernel-side changes for client-side,
lets us finish the complete auth/assoc handshake with higher
rates than the mandatory ones, without any further config.

However, the downside to this is that a broken station that
doesn't check the basic rates are supported before it tries
to connect will possibly not get any response to its auth
frame.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>