dt-bindings: serial: samsung: add exynosautov9-uart compatible

Add samsung,exynosautov9-uart dedicated compatible for representing
uart of Exynos Auto v9 SoC.

Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220701015226.32781-3-chanho61.park@samsung.com