ARM: dts: sun8i: Add PWM controller node for A23/A33

A23/A33 have a PWM controller that is compatible to the one on the A20.
Add a device node for it.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>