dt-bindings: hwmon: lltc,ltc4151: convert to dtschema

Convert the LTC4151 current and voltage sensor bindings to DT schema
format.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210921102832.143352-4-krzysztof.kozlowski@canonical.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>