thermal: imx8mm: Use dev_err_probe() to simplify error handling

dev_err_probe() can reduce code size, uniform error handling and record the
defer probe reason etc., use it to simplify the code.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1597129185-8460-2-git-send-email-Anson.Huang@nxp.com