thermal: sun8i: Fix r40 ths number

According to the spec, r40 has 2 thermal sensors.
Sensor0 located in the CPU, another in the GPU.

Fixes: dccc5c3b ("thermal/drivers/sun8i: Add thermal driver for H6/H5/H3/A64/A83T/R40")
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-on: sun8i-r40-bananapi-m2-ultra
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200106174639.20862-1-tiny.windzz@gmail.com

drivers/thermal/sun8i_thermal.c

@@ -565,7 +565,7 @@ static const struct ths_thermal_chip sun8i_h3_ths = {
 };
 
 static const struct ths_thermal_chip sun8i_r40_ths = {
-	.sensor_num = 3,
+	.sensor_num = 2,
 	.offset = 251086,
 	.scale = 1130,
 	.has_mod_clk = true,