leds: Use all-in-one vtime aware kcpustat accessor

We can now safely read user kcpustat fields on nohz_full CPUs.
Use the appropriate accessor.

[ mingo: Fixed build failure. ]

Reported-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com> (maintainer:LED SUBSYSTEM)
Cc: Pavel Machek <pavel@ucw.cz> (maintainer:LED SUBSYSTEM)
Cc: Dan Murphy <dmurphy@ti.com> (reviewer:LED SUBSYSTEM)
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Link: https://lkml.kernel.org/r/20191121024430.19938-6-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>