clk: rockchip: drop unnecessary header comment

clk: rockchip: drop unnecessary header comment

The internal clk header did contain a comment indicating that some of the
defined registers were shared over multiple clock controller variants.
In recent times, it was simply extended all the time and stopped providing
any meaningful information, so drop it and it's overlong line.

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