platform/x86: silead_dmi: Rename trekstor entries

Prefix the entries for trekstor tablets with trekstor_ and drop the
detailed model version (still available as comment in the dmi table)
to keep things within 80 chars.

This is a preparation patch for sorting all the entries alphabetically.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>