CHROMEOS: HID: Support for Logitech T651 Touchpad

CHROMEOS: HID: Support for Logitech T651 Touchpad

This touchpad is similar to the T650, but has a few notable
differences:

- It connects via Bluetooth as opposed to the Unifying Receiver

- The raw data reports are in a unique format appended to normal mouse
  reports. The mouse reports must be ignored. Putting this pad into
  raw data mode will work as the T650 does, but Nestor Lopez Casado of
  Logitech advises against as that mode as it's not officially
  supported.

BUG=chromium:223138
TEST=Manually tested on device. Will add base regression tests.

Signed-off-by: Andrew de los Reyes <adlr@chromium.org>
Change-Id: I9c6e3359f08508c54c47e79bec1bbc0121d0b06c
Reviewed-on: https://gerrit.chromium.org/gerrit/46683
Reviewed-by: Yufeng Shen <miletus@chromium.org>