ARM: dts: rockchip: add pwm nodes

This adds the necessary nodex and pinctrl settings for the Rockchip PWM-driver.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>

Modified to use the new clock defines and added rk3066 pins.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>