New FW added support for upto 20 clients in AP mode. Change the driver
to support this as well. FW reports it's max supported associations in
WMI_READY_EVENT. Some WMI commands/events use cidxtid field which is
limited to 16 cids. Use new cid/tid fields instead.

For Rx packets cid from rx descriptor is limited to 3 bits (0..7),
to find the real cid, compare transmitter address with the stored
stations mac address in the driver sta array.

EDMA FW still supports 8 stations. Extending the support to 20
stations will come later.
Signed-off-by: Ahmad Masri <amasri@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>