qcacmn: Set invalid bit in cookie for exception ring descriptor

On returning the msdu link descriptor to HW via WBM
release ring, the rx exception ring contents are not
zeroed. This could result in host reading stale ring
descriptor content in the scenario when HP is updated
even before the latest values are reflected in the ring
descriptor.

Fix is to set invalid bit in cookie for exception ring
descriptor and add cookie sanity check.

Change-Id: I01a294c92b260ebe8e584ef20e9550b1febec913
CRs-Fixed: 2730759