acpi: thermal: Fix error handling in the register function

The acpi_thermal_register_thermal_zone() is missing any error handling.
This needs to be fixed.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200629122925.21729-2-andrzej.p@collabora.com