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/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index 50cf402..03cb05a 100644
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -3329,7 +3329,7 @@ static DEVICE_ATTR(lpfc_static_vport, S_IRUGO,
  * @buf: Data buffer.
  * @count: Size of the data buffer.
  *
- * This function get called when an user write to the lpfc_stat_data_ctrl
+ * This function get called when a user write to the lpfc_stat_data_ctrl
  * sysfs file. This function parse the command written to the sysfs file
  * and take appropriate action. These commands are used for controlling
  * driver statistical data collection.