input: touchscreen: power off touch panel during suspend

Allow turn off touch panel power and reconfigure related GPIOs
to maximize power saving.

CRs-Fixed: 568957
Change-Id: I25d7dc8abbd6dae4c54ee14f8feaf5701f64fd95
Signed-off-by: Bingzhe Cai <bingzhec@codeaurora.org>