dt-bindings: hwmon: sparx5: use correct clock

SparX-5 temperature sensor uses system reference clock and not the AHB bus
clock as indicated by the register information [1].

So, correct the clock description as well the included example.

[1] https://microchip-ung.github.io/sparx-5_reginfo/reginfo_sparx-5.html?select=hsiowrap,temp_sensor,temp_sensor_cfg,clk_cycles_1us



Fixes: f5520753 ("dt-bindings: hwmon: Add Sparx5 temperature sensor")
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220809112209.241045-1-robert.marko@sartura.hr


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