cpuidle: Check the sign of index in cpuidle_reflect()

Avoid calling the governor's ->reflect method if the state index
passed to cpuidle_reflect() is negative.

This allows the analogous check to be dropped from menu_reflect(),
so do that too, and ensures that arbitrary error codes can be
passed to cpuidle_reflect() as the index with no adverse
consequences.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

diff --cc drivers/cpuidle/cpuidle.c
Simple merge

diff --cc drivers/cpuidle/governors/menu.c
Simple merge