target-ppc: Add "POWER" prefix to MMCRA PMU registers Since we started adding "POWER" prefix to 64bit PMU SPRs, let's finish the transition and fix MMCRA and define a supermode version of it. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Reviewed-by: Tom Musta <tommusta@gmail.com> Signed-off-by: Alexander Graf <agraf@suse.de>