Report finger origin ID to Windows

[imbushuo]

The current finger origin is not the real origin. Although I took the assumption that finger reports are not rearranged in a single series of inputs, this might not be always true. A few users have reported issues such as improper input rejections and cursor flips.

The device reports finger origins in uint16_t type and Windows wants something in uint8_t. Attempts of taking the lower 8 bits data have been tried but it is sub-optimal. Further studies on the Surface Pro trackpad input reports are required.

AB#681