checkpatch: allow for comments either side of a brace on case

When specifying case we may have comments and/or braces at the end without
actually having a 'statement'.  Allow for these to occur in any order.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>