checkpatch: possible modifiers -- handle multiple modifiers and trailing

Add support for multiple modifiers such as:

	int __one __two foo;

Also handle trailing known modifiers when defecting modifiers:

	int __one foo __read_mostly;

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>