thermal: rockchip: Support RK3576 SoC in the thermal driver

The RK3576 SoC has six TS-ADC channels: TOP, BIG_CORE, LITTLE_CORE,
DDR, NPU and GPU.

Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>
[ported to mainline, reworded commit message]
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>