mb/google/octopus: Enable Synaptics touchpad device

This change adds Synaptics device to phaser project.

BUG=b:110236590
TEST=emerge-octopus coreboot chromeos-bootimage
     reflash the coreboot to DUT,make sure the Synaptics Touchpad can work.

Change-Id: Icc1e8c35a9de54ed04187fcf219a72a592d3bd81
Signed-off-by: Xingyu <wuxy@bitland.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/27159
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/octopus/variants/baseboard/devicetree.cb

@@ -185,6 +185,15 @@ chip soc/intel/apollolake
 				register "probed" = "1"
 				device i2c 15 on end
 			end
+			chip drivers/i2c/hid
+				register "generic.hid" = ""PNP0C50""
+				register "generic.desc" = ""Synaptics Touchpad""
+				register "generic.irq" = "ACPI_IRQ_EDGE_LOW(GPIO_135_IRQ)"
+				register "generic.wake" = "GPE0_DW2_02"
+				register "generic.probed" = "1"
+				register "hid_desc_reg_offset" = "0x20"
+				device i2c 0x2c on end
+			end
 		end	# - I2C 6
 		device pci 17.3 on
 			chip drivers/i2c/generic