dt-bindings: clock: sifive: sync FU740 PRCI clock binding header

This commit sychronizes the header file for FU740 PRCI clocks with the
one from Linux 5.19.

The constant values are the same, but all constant names are changed
(most are just prefixed with FU740_).

Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>