iwlwifi: mvm: wake the correct mac80211 queue

iwl_mvm_start_mac_queues() takes a bitmap of the queues to wake.
When deferred tx is purged, set the bit of the hw_queue so
the correct queue will be waken up.

Fixes: 7e39a00d ("iwlwifi: mvm: start mac queues when deferred tx frames are purged")
Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>