iwlwifi: mvm: add support for new flush queue response

In the new api all the flush in the FW is done before we
get the response and in the response we only get the updated
read pointer and all queued packets don't get anymore rx_tx
per packet to free the queued packet, so driver needs to free
all queued packets on flushed queue at once after flush response.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210117130510.4bd0eca8c0ef.I1601aad2eb2cc83f6f73b8ca52be57bb9fd626ab@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>