lib: Don't print delegation CSRs if there is no S-Mode

If the platform doesn't support S-Mode don't print the delegation
registers.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>