cpu: imx_cpu: Print the CPU temperature for iMX8QM A72

iMX8QM registers two thermal devices for CPUs, get the temperature
from "cpu-thermal1" device for A72

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>