dt-bindings: hwmon: ti,ina2xx: Document ti,ina238 compatible string

Document the compatible string for the Texas Instruments INA238, this
device is a variant of the existing INA2xx devices and has the same
device tree bindings (shunt resistor).

Signed-off-by: Nathan Rossi <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml

···
       - ti,ina226
       - ti,ina230
       - ti,ina231
+      - ti,ina238
 
   reg:
     maxItems: 1