Thermal: x86_pkg_temp: fix krealloc() misuse in in pkg_temp_thermal_device_add()

If krealloc() returns NULL, it doesn't free the original. So any code
of the form 'foo = krealloc(foo, ...);' is almost certainly a bug.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>