wifi: iwlwifi: remove 'def_rx_queue' struct member

This is only ever initialized to zero, use a new define
for the default RX queue instead.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230816104355.e0c6fa57c162.I907bbb428cf99725f06a348c8dbce5d3dd877136@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>