qcacld-2.0: Add sanity check to avoid overflow in WMI event data

In WMA, data from firmware event buffer is used without
sanity checks for upper limit. This might lead to a potential
integer overflow further leading to buffer corruption.

Add sanity check to avoid integer overflow.

Change-Id: Id47e12015a4d46af24180b621b52ffcb17596c07
CRs-Fixed: 2113919
Bug: 68992426
Signed-off-by: Dennis Cagle <d-cagle@codeaurora.org>