Vegard Nossum reported:

> WARNING: at kernel/lockdep.c:2738 check_flags+0x142/0x160()

which happens due to:

 unsigned long long cpu_clock(int cpu)
 {
         unsigned long long clock;
         unsigned long flags;

         raw_local_irq_save(flags);

as lower level functions can take locks, we must not do that, use
proper lockdep-annotated irq save/restore.
Reported-by: NVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>