iwlwifi: mvm: fix reorder buffer for 9000 devices

The condition to check if reorder buffer ran out of
space is faulty, as it takes into account only the
NSSN.
In case the head SN was too far behind the reorder
buffer should move forward, regardless of the NSSN
status.
This caused the driver to release packets out of order
in some scenarios.

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>