iwlwifi: mvm: overwrite skb info later

We don't really need clear the skb's status area nor store the
dev_cmd into it until we really commit to the frame by handing
it to the transport - defer those operations until just before
we do that.

This doesn't entirely fix the bug with frames not getting sent
out after having been deferred due to DQA, because it doesn't
restore the info->driver_data[0] place that was already set to
zero (or another value) by the A-MSDU logic.

Fixes: 24afba76 ("iwlwifi: mvm: support bss dynamic alloc/dealloc of queues")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>