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>

drivers/clk/rockchip/clk.h

@@ -34,7 +34,6 @@ struct clk;
 #define HIWORD_UPDATE(val, mask, shift) \
 		((val) << (shift) | (mask) << ((shift) + 16))
 
-/* register positions shared by RK2928, RK3036, RK3066, RK3188, RK3228, RK3399 */
 #define RK2928_PLL_CON(x)		((x) * 0x4)
 #define RK2928_MODE_CON		0x40
 #define RK2928_CLKSEL_CON(x)	((x) * 0x4 + 0x44)