input: touchscreen: Add support for kernel command line parsing

Add support for kernel command line parsing in synaptic touch
screen driver. This enables dynamic touch driver selection for
a given target.

Change-Id: I9ba7b2162a6adad1eebae481c36d50f5804de9ad
Signed-off-by: Vishnuvardhan Prodduturi <vproddut@codeaurora.org>