iio: sx9500: add final devicetree support

This makes sx9500 driver usable on devicetree based platforms too.

Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Vlad Dogaru <ddvlad@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/proximity/sx9500.txt

@@ -0,0 +1,24 @@
+Semtech's SX9500 capacitive proximity button device driver
+
+Required properties:
+	- compatible: must be "semtech,sx9500"
+	- reg: i2c address where to find the device
+	- interrupt-parent : should be the phandle for the interrupt controller
+	- interrupts : the sole interrupt generated by the device
+
+	Refer to interrupt-controller/interrupts.txt for generic
+	interrupt client node bindings.
+
+Optional properties:
+	- reset-gpios: Reference to the GPIO connected to the device's active
+	  low reset pin.
+
+Example:
+
+sx9500@28 {
+	compatible = "semtech,sx9500";
+	reg = <0x28>;
+	interrupt-parent = <&gpio2>;
+	interrupts = <16 IRQ_TYPE_LEVEL_LOW>;
+	reset-gpios = <&gpio2 10 GPIO_ACTIVE_LOW>;
+};