dt-bindings:trivial-devices: Add sensortek,stk8312 and sensortek,s8ba50

Two simple devices. The stk8ba50 datasheet could be found via
google, but I only have the driver for the 8312.

Given they both seem to be 3 axis devices with a single interrupt
line, add them to trivial-devices.yaml
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210401174112.320497-6-jic23@kernel.org

Documentation/devicetree/bindings/trivial-devices.yaml

@@ -265,6 +265,10 @@ properties:
           - sensirion,sgpc3
             # Sensirion multi-pixel gas sensor with I2C interface
           - sensirion,sgp30
+            # Sensortek 3 axis accelerometer
+          - sensortek,stk8312
+            # Sensortek 3 axis accelerometer
+          - sensortek,stk8ba50
             # SGX Sensortech VZ89X Sensors
           - sgx,vz89x
             # Relative Humidity and Temperature Sensors