dt-bindings: pwm: allwinner: add v3s pwm compatible

The Allwinner V3s pwm peripheral is compatible with the pwm peripheral
inside the Allwinner A20.
This patch adds a compatible string for it.
Signed-off-by: Tobias Schramm <t.schramm@manjaro.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20210513203527.2072090-2-t.schramm@manjaro.org

Documentation/devicetree/bindings/pwm/allwinner,sun4i-a10-pwm.yaml

@@ -24,6 +24,9 @@ properties:
       - items:
           - const: allwinner,sun8i-a83t-pwm
           - const: allwinner,sun8i-h3-pwm
+      - items:
+          - const: allwinner,sun8i-v3s-pwm
+          - const: allwinner,sun7i-a20-pwm
       - items:
           - const: allwinner,sun50i-a64-pwm
           - const: allwinner,sun5i-a13-pwm