lib: sbi_hsm: Simplify hart_get_state() and hart_started() APIs

We remove redundant scratch parameter from sbi_hsm_hart_get_state()
and sbi_hsm_hart_started() APIs.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>