wmt(4): Reapply r358872 (by hselasky) modified to use
maximal input report size instead of wMaxPacketSize.

If the USB frame length is set to 1024 bytes, WMT_BSIZE, the EETI controller
will pack multiple touch events in the packet and the current code will only
process the first touch event.

As a result some important events are lost like releasing the finger from the
touchscreen.

Use the maximal input report size as buffer size instead.

PR: 244718
Tested by: Oskar Holmlund <oskar.holmlund@ohdata.se>, wulf
MFC after: 3 days
Discussed with: hselasky