forked from Mirrors/opensbi

As-per SBI specification, all firmware counters are always 64 bits wide so let us update the SBI PMU implementation to reflect this fact. Signed-off-by: Anup Patel <apatel@ventanamicro.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Atish Patra <atishp@rivosinc.com>