input: synaptics_dsx_2.6: update driver to enable touch S332U

Synaptics reference driver V2.6 is being cleaned up to enable touch
controller S332U. Add Kconfig and Makefile changes to enable Synaptics dsx
V2.6 driver's compilation.
Clean checkpatch errors.

CRs-Fixed: 943896
Change-Id: I7e79e9ee321b7a7c90d27f065281dc73cee65391
Signed-off-by: Mao Li <maol@codeaurora.org>
Signed-off-by: Venkata Prahlad Valluru <vvalluru@codeaurora.org>