Perf: arm64: Update PMU force reset

Bring all cores online before doing a force reset for PMU.
This is required in order to handle corner case related to
freeing of IRQs for offline cores.

Change-Id: I091d9039e6554099ff4dd80d4a69cabe8eff3138
Signed-off-by: Sheetal Sahasrabudhe <sheetals@codeaurora.org>