This patch does few cosmetic improvements to HART feature detection:
1. Remove sbi_ perfix from HART feature detection functions
because all local/static functions in sbi_hart.c don't have
sbi_ prefix
2. Remove sbi_hart_set_feature() because it's quite small and
local/static in sbi_hart.c
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>