clk: rockchip: add register offset of the cores select parent

The cores select parent register is special on RK3588.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20221018151407.63395-5-sebastian.reichel@collabora.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>