wil6210: add verification for cid upper bound

max_assoc_sta can receive values (from the user or from the FW)
that are higher than WIL6210_MAX_CID.
Verify that cid doesn't exceed the upper bound of WIL6210_MAX_CID.

Signed-off-by: Alexei Avshalom Lazar <ailizaro@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>