tools/thermal: Fix common realloc mistake

If the 'realloc' fails, the thermal zones pointer is set to NULL. This
makes all thermal zones references which were previously successfully
initialized to be lost.

[dlezcano] : Fixed indentation

Signed-off-by: zhang jiao <zhangjiao2@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20241114084039.42149-1-zhangjiao2@cmss.chinamobile.com


Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>