Wifi: add 3 new fields to ConnectionCapabilities.

Add channel bandwidth, max number of Rx spatial streams, max number of
Tx spatial streams to connectionCapabilitie() which is derived from
association request and response frames after a new association.

bug: 147390882
Test: VTS test
Test: manual test with various phones and APs.
Change-Id: Iaeb5e0419887b766ec1a4cb13843494539aa3ddd