ARM: dts: suniv: f1c100s: add PWM node

The Allwinner F1C100s family of SoCs contain a PWM controller compatible
to the one used in the A20 chip.
Add the DT node so that any users can simply enable it in their board
DT.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20221107005433.11079-3-andre.przywara@arm.com


Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>