forked from Mirrors/opensbi

OpenSBI doesn't handle PMU counters for now. Delegate the overflow counter to S-mode always. Reviewed-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Anup Patel <anup.patel@wdc.com> Signed-off-by: Atish Patra <atish.patra@wdc.com>