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 6bcb1c73162312e2a721163274daae8c647dbedd
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 65b5bdff4d9b215f15a8bb85464e34e1b1c80fcb.