iwlwifi: mvm: ignore BAID for SN smaller than SSN

When we get SN that is smaller than SSN of the aggregation,
we shouldn't apply any reordering on them.
Further more, HW NSSN will be zeroed, which can cause us
to make some invalid decisions.
Detect the situation and invalidate the BAID.

Fixes: b915c101

 ("iwlwifi: mvm: add reorder buffer per queue")
Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>