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