Updates for WSP driver:

1) Add support for page back/forward.
2) While doing HOR scrolling, disable VER scrolling.
3) Checking dx_sum and dy_sum before emulate right button, this can
avoids unexpected right button press.
4) Fix stable pointer operation when emulating middle button.

Submitted by:	Huang Wen Hui <huanghwh@gmail.com>
MFC after:	2 weeks