iwlwifi: move QoS into context

Since mac80211 doesn't currently enable/disable
QoS per interface, we can't yet do it properly,
but we can already prepare for it and move the
QoS data and command ID into the context struct.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>