watch_queue: Drop references to /dev/watch_queue

The merged API doesn't use a watch_queue device, but instead relies on
pipes, so let the documentation reflect that.

Fixes: f7e47677e39a ("watch_queue: Add a key/keyring notification facility")
Signed-off-by: Gabriel Krisman Bertazi <[e-mail]>
Signed-off-by: David Howells <[e-mail]>
Acked-by: Jarkko Sakkinen <[e-mail]>
Reviewed-by: Ben Boeckel <[e-mail]>

Documentation/security/keys/core.rst

···
 
      "key" is the ID of the key to be watched.
 
-     "queue_fd" is a file descriptor referring to an open "/dev/watch_queue"
-     which manages the buffer into which notifications will be delivered.
+     "queue_fd" is a file descriptor referring to an open pipe which
+     manages the buffer into which notifications will be delivered.
 
      "filter" is either NULL to remove a watch or a filter specification to
      indicate what events are required from the key.

samples/Kconfig

···
 	depends on CC_CAN_LINK
 
 config SAMPLE_WATCH_QUEUE
-	bool "Build example /dev/watch_queue notification consumer"
+	bool "Build example watch_queue notification API consumer"
 	depends on CC_CAN_LINK && HEADERS_INSTALL
 	help
 	  Build example userspace program to use the new mount_notify(),

samples/watch_queue/watch_test.c

···
 // SPDX-License-Identifier: GPL-2.0
-/* Use /dev/watch_queue to watch for notifications.
+/* Use watch_queue API to watch for notifications.
  *
  * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells ([e-mail])

security/keys/Kconfig

···
 	bool "Provide key/keyring change notifications"
 	depends on KEYS && WATCH_QUEUE
 	help
-	  This option provides support for getting change notifications on keys
-	  and keyrings on which the caller has View permission.  This makes use
-	  of the /dev/watch_queue misc device to handle the notification
-	  buffer and provides KEYCTL_WATCH_KEY to enable/disable watches.
+	  This option provides support for getting change notifications
+	  on keys and keyrings on which the caller has View permission.
+	  This makes use of pipes to handle the notification buffer and
+	  provides KEYCTL_WATCH_KEY to enable/disable watches.