scripts/spelling.txt: add "an user" pattern and fix typo instances

Fix typos and add the following to the scripts/spelling.txt:

  an user||a user
  an userspace||a userspace

I also added "userspace" to the list since it is a common word in Linux.
I found some instances for "an userfaultfd", but I did not add it to the
list.  I felt it is endless to find words that start with "user" such as
"userland" etc., so must draw a line somewhere.

Link: http://lkml.kernel.org/r/1481573103-11329-4-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index 48f9471..f64d656 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -851,7 +851,7 @@
 
 	if (hdev) {
 		if (hci_pi(sk)->channel == HCI_CHANNEL_USER) {
-			/* When releasing an user channel exclusive access,
+			/* When releasing a user channel exclusive access,
 			 * call hci_dev_do_close directly instead of calling
 			 * hci_dev_close to ensure the exclusive access will
 			 * be released and the controller brought back down.
@@ -1172,7 +1172,7 @@
 				/* In case the transport is already up and
 				 * running, clear the error here.
 				 *
-				 * This can happen when opening an user
+				 * This can happen when opening a user
 				 * channel and HCI_AUTO_OFF grace period
 				 * is still active.
 				 */
@@ -1190,7 +1190,7 @@
 		if (!hci_sock_gen_cookie(sk)) {
 			/* In the case when a cookie has already been assigned,
 			 * this socket will transition from a raw socket into
-			 * an user channel socket. For a clean transition, send
+			 * a user channel socket. For a clean transition, send
 			 * the close notification first.
 			 */
 			skb = create_monitor_ctrl_close(sk);