iwlwifi: mvm: disable RX queue notification for a000 devices

For a000 devices, we don't really have multi RX queue for now,
until we have the RX queue configuration API.
Disable RX queue notification for now.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>