dt-bindings: hwmon: tmp108: add optional interrupts and #thermal-sensor-cells

The tmp108 does have an alert output that can be used as interrupt source
and can of course also be used as part of a thermal sensor setup for things
like thermal-based cpu frequencies, so document the necessary properties.
Signed-off-by: Heiko Stuebner <heiko.stuebner@bq.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/tmp108.txt

@@ -7,6 +7,10 @@ Requires node properties:
 - compatible : "ti,tmp108"
 - reg : the I2C address of the device. This is 0x48, 0x49, 0x4a, or 0x4b.
 
+Optional properties:
+- interrupts: Reference to the TMP108 alert interrupt.
+- #thermal-sensor-cells: should be set to 0.
+
 Example:
 	tmp108@48 {
 		compatible = "ti,tmp108";