spi: dt-bindings: samsung: Add Exynos4210 SPI

Document samsung,exynos4210-spi compatible which is already used on
several Exynos SoCs.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Chanho Park <chanho61.park@samsung.com>
Link: https://lore.kernel.org/r/20220626112838.19281-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/samsung,spi.yaml

@@ -20,6 +20,7 @@ properties:
           - samsung,s3c2443-spi # for S3C2443, S3C2416 and S3C2450
           - samsung,s3c6410-spi
           - samsung,s5pv210-spi # for S5PV210 and S5PC110
+          - samsung,exynos4210-spi
           - samsung,exynos5433-spi
           - tesla,fsd-spi
       - const: samsung,exynos7-spi