ARM: sched_clock: Remove unused needs_suspend member

The needs_suspend member is unused now that we always do the
suspend/resume handling (see 6a4dae5e (ARM: 7565/1: sched: stop
sched_clock() during suspend, 2012-10-23)).

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>