time: prevent the loop in timespec_add_ns() from being optimised away

time: prevent the loop in timespec_add_ns() from being optimised away

upstream commit: 38332cb98772f5ea757e6486bed7ed0381cb5f98

Since some architectures don't support __udivdi3().

Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc:  Sedat Dilek <sedat.dilek@googlemail.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>