ARM: dts: msm: Add support for Synaptics touch controller

When 8x10 is equipped with 720p display panel, touch controller that
comes with the panel is from Synaptics. This patch provides support
for Synaptics touch controller to enable touch on 720p panel.

CRs-Fixed: 539071
Change-Id: I12109c39356c1f62ea7a637ea441f743f525d530
Signed-off-by: Chun Zhang <chunz@codeaurora.org>