wifi: iwlwifi: mvm: prefer RCU_INIT_POINTER()

For constant values we don't need rcu_assign_pointer(),
use RCU_INIT_POINTER() 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/20230418122405.7b400d21a27f.Iccdef9d777677390a9881c88b06c0ed13a83d978@changeid


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