dt-bindings: iio: adc: amlogic,meson-saradc: Add GXLX SoC compatible

dt-bindings: iio: adc: amlogic,meson-saradc: Add GXLX SoC compatible

Add a compatible string for the GXLX SoC. It's very similar to GXL but
has three additional bits in MESON_SAR_ADC_REG12 for the three MPLL
clocks.

Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://patch.msgid.link/20250330101922.1942169-2-martin.blumenstingl@googlemail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>