realtek: clk: add rtl9607 clock support

realtek: clk: add rtl9607 clock support

This commit adds support for RTL9607C/RTL8198D clocks to the existing
clk-rtl83xx driver. Setting clock rates is not supported due to
lack of knowledge on this topic at the moment. Clocks for CPU1, SRAM
and SPI can also be calculated but not included in this commit.

Since the registers, calculations are widely different to RTL83XX it
was decide to have different clk_ops for RTL960X.

The code was partly based on naseef's work with some changes to
integrate it into the clk-rtl83xx driver.

Tested-by: Ahmed Naseef <naseefkm@gmail.com>
Signed-off-by: Rustam Adilov <adilov@tutamail.com>
Link: https://github.com/openwrt/openwrt/pull/22080
Signed-off-by: Robert Marko <robimarko@gmail.com>