checkpatch: correctly handle type spacing in the face of modifiers

We need to handle interspersed modifiers in the middle of pointer types,
for example:

	void * __user * __user bar;

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