KVM: selftests: aarch64: vPMU test for validating user accesses

KVM: selftests: aarch64: vPMU test for validating user accesses

Add a vPMU test scenario to validate the userspace accesses for
the registers PM{C,I}NTEN{SET,CLR} and PMOVS{SET,CLR} to ensure
that KVM honors the architectural definitions of these registers
for a given PMCR.N.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231020214053.2144305-13-rananta@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>