thermal: core: Fix resources release in error paths in thermal_zone_device_register()

Reorder error handling code in order to fix some resources leaks in some
cases:
   - 'tz' would leak if 'thermal_zone_create_device_groups()' fails
   - memory allocated by 'thermal_zone_create_device_groups()' would leak
     if 'device_register()' fails

With this patch, we now have 2 error handling paths: one before
'device_register()', and one after it.
This is needed because some resources are released in 'thermal_release()'.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>