clk: sifive: duplicate the macro definitions for the time being

This is a temporary patch in whole patch set. We are going to change the
macro name in dt-binding, in order to avoid breaking the driver build
and git bisect, add these macro definitions for the time being, and we
will remove them later.

Signed-off-by: Zong Li <zong.li@sifive.com>
Link: https://lore.kernel.org/r/8cfd57f01cfb59adb716eb13ca0c8250c246dcb2.1646388139.git.zong.li@sifive.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>