wlcore: use proper values for supported local rates

We were setting all the rates bits when starting the AP role.  Instead
of doing this, we should set only the rates we really support
(eg. MIMO rates or wide-channel rates).  This commit changes that so
that we always use the default rates (basic rates + MCS0-7) and add
the values returned by the ap_get_mimo_wide_rate_mask operation.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>