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/Documentation/networking/cdc_mbim.txt b/Documentation/networking/cdc_mbim.txt
index a15ea60..b9482ca 100644
--- a/Documentation/networking/cdc_mbim.txt
+++ b/Documentation/networking/cdc_mbim.txt
@@ -38,7 +38,7 @@
 ===========
 
 MBIM functions are inactive when unmanaged. The cdc_mbim driver only
-provides an userspace interface to the MBIM control channel, and will
+provides a userspace interface to the MBIM control channel, and will
 not participate in the management of the function. This implies that a
 userspace MBIM management application always is required to enable a
 MBIM function.
@@ -200,7 +200,7 @@
 The DSS VLAN subdevices are used as a practical interface between the
 shared MBIM data channel and a MBIM DSS aware userspace application.
 It is not intended to be presented as-is to an end user. The
-assumption is that an userspace application initiating a DSS session
+assumption is that a userspace application initiating a DSS session
 also takes care of the necessary framing of the DSS data, presenting
 the stream to the end user in an appropriate way for the stream type.