platform/x86: thinkpad-lmi: Remove unused display_name member from struct tlmi_pwd_setting

The struct tlmi_pwd_setting display_name member is initialized,
but never read. Remove it and the TLMI_PWDTYPE_MAXLEN define.

While at it also remove some other unused [MAX]LEN defines.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210531135911.82582-1-hdegoede@redhat.com