[PATCH] headers_check: remove <asm/timex.h> from user export

There's useful stuff in <linux/timex.h> but <asm/timex.h> has nothing for
userspace.  Stop exporting it, and include it only from within the existing
#ifdef __KERNEL__ part of <linux/timex.h>

This fixes a 'make headers_check' failure on i386 because asm-i386/timex.h
includes both asm-i386/tsc.h and asm-i386/processor.h, neither of which are
exported to userspace.  It's not entirely clear _why_ it includes either of
these, but it does.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>