platform/x86: think-lmi: Fix memory leak when showing current settings

In the Linux kernel, the following vulnerability has been resolved: platform/x86: think-lmi: Fix memory leak when showing current settings When retriving a item string with tlmi_setting(), the result has to be freed using kfree(). In current_value_show() however, malformed item strings are not freed, causing a memory leak. Fix this by eliminating the early return responsible for this.