mb/google/poppy/variants/nami: Prevent leakage with touchscreen on Pantheon

We found GPP_C3 keeps high when system in S0ix mode. It caused 1.8V
leakage. To fix this problem, add GPP_C3 into config for Pantheon
Synaptics touchscreen.

TEST=Let DUT in S0ix mode and check GPP_C3 is normal.

Change-Id: Idb2dab93178af1dae54265e49522b473b69a35af
Signed-off-by: Crystal Lin <crystal_lin@compal.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/27177
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
1 file changed