dt-bindings: iio: temperature: melexis,mlx90614: Document MLX90615 support

dt-bindings: iio: temperature: melexis,mlx90614: Document MLX90615 support

Document support for MLX90615 Infra Red Thermometer, which seems to
be the predecesor of MLX90614 . There are significant differences in
the register layout compared to MLX90614, but the functionality of
the device is virtually identical.

Acked-by: Crt Mori <cmo@melexis.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20230510102251.10118-1-marex@denx.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>