Input: sentelic - enabling absolute coordinates output for newer hardware

Input: sentelic - enabling absolute coordinates output for newer hardware

BugLink: http://bugs.launchpad.net/bugs/969334

- Hooking multi-finger coordinates output with kernel multitouch library;
- Enabling absolute coordinates output for Cx+ hardware. The older hardware
  performs much better in relative mode; thus relative mode related code
  are preserved.

Part of the code is based on the work done by Oskari Saarenmaa <os@ohmu.fi>,
which was used to support the clickpad found on ASUS UX21/31 Ultrabook.
On the other hand, the FSP found on UX21/31 doesn't have hardware capability
register other than PnP ID, which means that we'll have to figure out an
alternative approach to identify such pad correctly; otherwise, blindly
adding INPUT_PROP_BUTTONPAD property may compatability issues amongst
existing FSPs.

Signed-off-by: Tai-hwa Liang <avatar@sentelic.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
(cherry picked from commit a4c85075f00d56b38f5c277ab89f9aaad69eb17b)

Signed-off-by: Eric Miao <eric.miao@canonical.com>
Acked-by: Leann Ogasawara <leann.ogasawara@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>