ft5x06: Set input property bit to indicate a direct input device

Prop bit is checked in userspace and must be set in
driver in order to be recognized correctly, since it defaults
to mouse pointer.

Change-Id: Ibdc78547e6376e6db54db75b1423718d13afaaa7
Signed-off-by: Amy Maloche <amaloche@codeaurora.org>