Revert "iwlwifi: mvm: drop non VO frames when flushing"

Revert "iwlwifi: mvm: drop non VO frames when flushing"

This is now implemented by mac80211 (commit below).
mac80211 will flush/drop the frames on the queues before
suspending / disconnecting.
It will then send the deauth and wait until the queues are
empty.

commit a2a9c8f2c24cb42a7a3bbf9131bc507c25229f81
Author: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Date:   Wed Jan 7 15:42:39 2015 +0200

    mac80211: let flush() drop packets when possible

This reverts commit 949db61760ecf6430f5aaf35132bdebc0e518ce6.