drivers/thermal/rcar_gen3_thermal: Improve logging during probe

drivers/thermal/rcar_gen3_thermal: Improve logging during probe

When setting up a new board, a plain "Can't register thermal zone"
didn't help me much because the thermal zones in DT were all fine. I
just had a sensor entry too much in the parent TSC node. Reword the
failure/success messages to contain the sensor number to make it easier
to understand which sensor is affected. Example output now:

rcar_gen3_thermal e6198000.thermal: Sensor 0: Loaded 1 trip points
rcar_gen3_thermal e6198000.thermal: Sensor 1: Loaded 1 trip points
rcar_gen3_thermal e6198000.thermal: Sensor 2: Loaded 1 trip points
rcar_gen3_thermal e6198000.thermal: Sensor 3: Can't register thermal zone

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20220610200500.6727-1-wsa+renesas@sang-engineering.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>