iwlwifi: rework the iwlwifi debugfs structure

The generic part of the driver now creates all debugfs
directories. It creates a root directory directly in
the the root of the debugfs filesystem and within that
directories for each device, named after the device ID
of the devices iwlwifi is attached to.

In the cfg80211/mac80211 directory there's now a link
to the toplevel iwlwifi debugfs directory to make it
easier to find the debugfs files.

Signed-off-by: Meenakshi Venkataraman <meenakshi.venkataraman@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/iwlwifi/iwl-op-mode.h

@@ -134,7 +134,8 @@ struct iwl_cfg;
 struct iwl_op_mode_ops {
 	struct iwl_op_mode *(*start)(struct iwl_trans *trans,
 				     const struct iwl_cfg *cfg,
-				     const struct iwl_fw *fw);
+				     const struct iwl_fw *fw,
+				     struct dentry *dbgfs_dir);
 	void (*stop)(struct iwl_op_mode *op_mode);
 	int (*rx)(struct iwl_op_mode *op_mode, struct iwl_rx_cmd_buffer *rxb,
 		  struct iwl_device_cmd *cmd);