lib: sbi_hsm: Remove scratch parameter from hart_started_mask() API

The scratch parameter in sbi_hsm_hart_started_mask() API is now
redundant hence removing it.

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>