Implement device functions for motor board

Implement IsDetected, InitDevice, Reset for motor board.
Add motor board instance to fpga_tio.

To reset motor, move motor toward release direction for an excessive
distance such that it is fixed.

BUG=chromium:685530
TEST=on test_server, runs p.motor_board.Touch(func) and
p.motor_board.Release(func), where func is one of ['Vol Up', 'Vol Down',
'Mute', 'Call', 'Hang Up']

Change-Id: I6b7d3f39df4d1feee93309c593b4759e02b5ff32
Reviewed-on: https://chromium-review.googlesource.com/479615
Commit-Ready: Cheng-Yi Chiang <cychiang@chromium.org>
Tested-by: Cheng-Yi Chiang <cychiang@chromium.org>
Reviewed-by: Wai-Hong Tam <waihong@google.com>
3 files changed