Bluetooth: Improve comments on the HCI_Delete_Store_Link_Key issue

Some Bluetooth controllers doesn't support this command so we first
need to check for its support before sending it. This patch adds a
lengthful commentary about this.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

net/bluetooth/hci_core.c

@@ -597,7 +597,15 @@ static void hci_init3_req(struct hci_request *req, unsigned long opt)
 	struct hci_dev *hdev = req->hdev;
 	u8 p;
 
-	/* Only send HCI_Delete_Stored_Link_Key if it is supported */
+	/* Some Broadcom based Bluetooth controllers do not support the
+	 * Delete Stored Link Key command. They are clearly indicating its
+	 * absence in the bit mask of supported commands.
+	 *
+	 * Check the supported commands and only if the the command is marked
+	 * as supported send it. If not supported assume that the controller
+	 * does not have actual support for stored link keys which makes this
+	 * command redundant anyway.
+         */
 	if (hdev->commands[6] & 0x80) {
 		struct hci_cp_delete_stored_link_key cp;