dt-bindings: (hwmon/sbtsi_temp) Add SB-TSI hwmon driver bindings

Document device tree bindings for AMD SB-TSI emulated temperature
sensor.

Signed-off-by: Kun Yi <kunyi@google.com>
Link: https://lore.kernel.org/r/20201211215427.3281681-4-kunyi@google.com


Reviewed-by: Rob Herring <robh@kernel.org>
[groeck: Fixed subject]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>