spi: spi-rockchip: Add rk3568-spi compatible

This adds a compatible string for the SPI controller found on
the RK3566 and RK3568 SoCs.

Signed-off-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>
Link: https://lore.kernel.org/r/20211126154344.724316-2-frattaroli.nicolas@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/Documentation/devicetree/bindings/spi/spi-rockchip.yaml b/Documentation/devicetree/bindings/spi/spi-rockchip.yaml
index 7f987e7..52a78a2 100644
--- a/Documentation/devicetree/bindings/spi/spi-rockchip.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-rockchip.yaml
@@ -33,6 +33,7 @@
               - rockchip,rk3328-spi
               - rockchip,rk3368-spi
               - rockchip,rk3399-spi
+              - rockchip,rk3568-spi
               - rockchip,rv1126-spi
           - const: rockchip,rk3066-spi