Updates to drivers/perf to support Arm SystemReady IR

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2071841
Tested: This is one of a series of patch sets to enable Arm SystemReady IR
 support in the kernel for NXP i.MX8 platforms.  This set just adds
 a couple of small patches for the perf subsysyem.  This set has been
 tested via simple boot tests, use of perf, and of course the CI loop.

This is part of a series of patch sets to enable support for Arm SystemReady IR
compliant platforms in RHEL.  There were just a couple of minor updates needed
to drivers/perf -- one arm64-specific and another to provide more accurate
results across all arches.

Signed-off-by: Al Stone <ahs3@redhat.com>