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>

riscv: dts: add fu740 support

Add dts support for fu740. The HiFive Unmatched support is based on
fu740 cpu and drivers in following patch set.

Signed-off-by: Green Wan <green.wan@sifive.com>
[greentime.hu: set fu740 speed to 1.2GHz]
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>

riscv: dts: add fu740 support

Add dts support for fu740. The HiFive Unmatched support is based on
fu740 cpu and drivers in following patch set.

Signed-off-by: Green Wan <green.wan@sifive.com>
[greentime.hu: set fu740 speed to 1.2GHz]
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>