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.

Change-Id: Id00b69a128d2c4df4a3ef85583bbe44590ff557c
Signed-off-by: Alexei Avshalom Lazar <ailizaro@codeaurora.org>