Tmu_get_temp will get called as a part of sensor registration via
devm_thermal_zone_of_sensor_register(). To prevent it from retruning
bogus data we need to enable sensor monitoring before that. Looking at
the datasheet (i.MX8MQ RM) there doesn't seem to be any harm in
enabling them all, so, for the sake of simplicity, change the code to
do just that.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-imx@nxp.com
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org