platform/x86: think-lmi: Simplify tlmi_analyze() error handling a bit

Creating the tlmi_pwd_setting structs can only fail with -ENOMEM, set
ret to this once and simplify the error handling a bit.

Tested-by: Mark Pearson <markpearson@lenovo.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20211118114150.271274-2-hdegoede@redhat.com