hwmon: (coretemp) Avoid leaving around dangling pointer

Storing the struct temp_data pointer allocated from create_core_data()
when returning an error has the potential of leaving around a pointer
to freed memory. Reset it to NULL for error returns.
Reported-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NGuenter Roeck <guenter.roeck@ericsson.com>
Acked-by: NJean Delvare <khali@linux-fr.org>

drivers/hwmon/coretemp.c

@@ -506,6 +506,7 @@ static int create_core_data(struct platform_device *pdev,
 
 	return 0;
 exit_free:
+	pdata->core_data[attr_no] = NULL;
 	kfree(tdata);
 	return err;
 }