platform: Replace CLINT library usage with ACLINT library

The ACLINT devices are backward compatible with SiFive CLINT
so we replace all CLINT library usage in various platforms
with ACLINT library. As a result of this replacement, the
CLINT library is not used by any part of OpenSBI hence we
remove it.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Xiang W <wxjstz@126.com>