wifi: iwlwifi: mention the response structure in the kerneldoc

Add a comment to mention the structure used for the response for the
flush command.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Link: https://lore.kernel.org/r/20230127002430.422c9fbac12c.I2da0954d1c62007b5f01faf06df3e4081e52204f@changeidSigned-off-by: Gregory Greenman <gregory.greenman@intel.com>

drivers/net/wireless/intel/iwlwifi/fw/api/commands.h

@@ -153,6 +153,7 @@ enum iwl_legacy_cmds {
 
 	/**
 	 * @TXPATH_FLUSH: &struct iwl_tx_path_flush_cmd
+	 *	response in &struct iwl_tx_path_flush_cmd_rsp
 	 */
 	TXPATH_FLUSH = 0x1e,