platform/x86: silead_dmi: Add entry for the Yours Y8W81 tablet

Add an entry with touchscreen info for the Yours Y8W81 8" tablet.

This tablet has the same case and mostly the same internals as the Chuwi
Vi8. Both seem to be from an ODM called inet-tek. Both are labelled:
"INET-I86M-REVxx" on the PCB, with the Chuwi Vi8 being REV03 (and having
an ALC5640 audio codec) and the Yours Y8W81 being REV21 (and having an
ALC5651 audio codec). The wifi, accelerometer and touchscreen are
identical on both.

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