iwlwifi: iwl-drv: Provide descriptions debugfs dentries

Also demote a non-conforming kernel-doc function header.

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/intel/iwlwifi/iwl-drv.c:124: warning: Function parameter or member 'dbgfs_drv' not described in 'iwl_drv'
 drivers/net/wireless/intel/iwlwifi/iwl-drv.c:124: warning: Function parameter or member 'dbgfs_trans' not described in 'iwl_drv'
 drivers/net/wireless/intel/iwlwifi/iwl-drv.c:124: warning: Function parameter or member 'dbgfs_op_mode' not described in 'iwl_drv'
 drivers/net/wireless/intel/iwlwifi/iwl-drv.c:1329: warning: Function parameter or member 'ucode_raw' not described in 'iwl_req_fw_callback'
 drivers/net/wireless/intel/iwlwifi/iwl-drv.c:1329: warning: Function parameter or member 'context' not described in 'iwl_req_fw_callback'

Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Intel Linux Wireless <linuxwifi@intel.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200910065431.657636-16-lee.jones@linaro.org

drivers/net/wireless/intel/iwlwifi/iwl-drv.c

@@ -102,6 +102,9 @@ static struct dentry *iwl_dbgfs_root;
  * @fw_index: firmware revision to try loading
  * @firmware_name: composite filename of ucode file to load
  * @request_firmware_complete: the firmware has been obtained from user space
+ * @dbgfs_drv: debugfs root directory entry
+ * @dbgfs_trans: debugfs transport directory entry
+ * @dbgfs_op_mode: debugfs op_mode directory entry
  */
 struct iwl_drv {
 	struct list_head list;
@@ -1319,7 +1322,7 @@ static void _iwl_op_mode_stop(struct iwl_drv *drv)
 	}
 }
 
-/**
+/*
  * iwl_req_fw_callback - callback when firmware was loaded
  *
  * If loaded successfully, copies the firmware into buffers