arm64: dts: imx8mp: Correct thermal sensor index

The TMU has two temperature measurement sites located on the chip. The
probe 0 is located inside of the ANAMIX, while the probe 1 is located near
the ARM core. This has been confirmed by checking with HW design team and
checking RTL code.

So correct the {cpu,soc}-thermal sensor index.

Fixes: 30cdd62d ("arm64: dts: imx8mp: Add thermal zones support")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>