KVM: arm64: Add handling of AArch32 PCMEID{2,3} PMUv3 registers

Despite advertising support for AArch32 PMUv3p1, we fail to handle
the PMCEID{2,3} registers, which conveniently alias with the top
bits of PMCEID{0,1}_EL1.

Implement these registers with the usual AA32(HI/LO) aliasing
mechanism.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>