Documentation: Use "while" instead of "whilst"

Whilst making an unrelated change to some Documentation, Linus sayeth:

  | Afaik, even in Britain, "whilst" is unusual and considered more
  | formal, and "while" is the common word.
  |
  | [...]
  |
  | Can we just admit that we work with computers, and we don't need to
  | use þe eald Englisc spelling of words that most of the world never
  | uses?

dictionary.com refers to the word as "Chiefly British", which is
probably an undesirable attribute for technical documentation.

Replace all occurrences under Documentation/ with "while".

Cc: David Howells <dhowells@redhat.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt
index a9ae82f..9ccfd1b 100644
--- a/Documentation/filesystems/xfs.txt
+++ b/Documentation/filesystems/xfs.txt
@@ -417,7 +417,7 @@
 	filesystem from ever unmounting fully in the case of "retry forever"
 	handler configurations.
 
-	Note: there is no guarantee that fail_at_unmount can be set whilst an
+	Note: there is no guarantee that fail_at_unmount can be set while an
 	unmount is in progress. It is possible that the sysfs entries are
 	removed by the unmounting filesystem before a "retry forever" error
 	handler configuration causes unmount to hang, and hence the filesystem