dt-bindings: iio: sx9324: Add input analog gain

Allow setting the configure the input analog gain.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220429220144.1476049-8-gwendal@chromium.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/proximity/semtech,sx9324.yaml

@@ -143,6 +143,17 @@ properties:
     description:
       Pre-charge input resistance in Ohm.
 
+  semtech,input-analog-gain:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 3
+    description: |
+      Defines the input antenna analog gain
+      0: x1.247
+      1: x1 (default)
+      2: x0.768
+      3: x0.552
+
 required:
   - compatible
   - reg