dt-bindings: serial: samsung_uart: Document Exynos5433 compatible

dt-bindings: serial: samsung_uart: Document Exynos5433 compatible

Document the Exynos5433 UART compatible, supported since commit
31ec77aca72e ("serial: samsung: Add the support for Exynos5433 SoC").

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220202151310.285561-2-krzysztof.kozlowski@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>