[PATCH] ktime: Fix signed / unsigned mismatch in ktime_to_ns

The 32 bit implementation of ktime_to_ns returns unsigned value, while the
64 bit version correctly returns an signed value.  There is no current user
affected by this, but it has to be fixed, as ktime values can be negative.

Pointed-out-by: Helmut Duregger <Helmut.Duregger@student.uibk.ac.at>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>