forked from Mirrors/opensbi

Directly implement frequency discovery, making the sysctl code unnecessary. While at it, Move all macro definitions from platform.c into platform.h and cleanup that file, removing the need for the Apache 2.0 license and Canaan Inc copyright. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Anup Patel <anup.patel@wdc.com>