dt-bindings: iio: amplifiers: add adl8113

dt-bindings: iio: amplifiers: add adl8113

Add devicetree bindings for the ADL8113 Low Noise Amplifier.

The bindings include support for specifying gain values of external
amplifiers connected to the two external bypass paths (A and B). These
optional properties allow the gain values to be selectable via the
hardwaregain attribute, enabling complete devicetree description of
the signal chain including external components.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>