timers, sched: Correct the comments for tick_sched_timer()

timers, sched: Correct the comments for tick_sched_timer()

In the comments of function tick_sched_timer(), the sentence
"timer->base->cpu_base->lock held" is not right.

In function __run_hrtimer(), before call timer->function(),
the cpu_base->lock has been unlocked.

Signed-off-by: liu chuansheng <[email protected]>
Cc: [email protected]
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/1351098455.15558.1421.camel@cliu38-desktop-build
Signed-off-by: Ingo Molnar <[email protected]>