mb/google/zork: expose stop gpio for trembyle

In CB:43701 the trembyle touchscreen parameters were not updated
to expose the stop gpio properly.

BUG=b:162973325

Change-Id: I6f5da1c556ba1c6ccabf699491d3b635aa79f7c0
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44254
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/zork/variants/trembyle/overridetree.cb

@@ -73,6 +73,8 @@ chip soc/amd/picasso
 			# 32ms: Rise time of the reset line
 			# 20ms: Firmware ready time
 			register "reset_delay_ms" = "32 + 20"
+			register "stop_gpio" = "ACPI_GPIO_OUTPUT_ACTIVE_LOW(GPIO_144)"
+			register "stop_off_delay_ms" = "1"
 			register "has_power_resource" = "1"
 			device i2c 39 on end
 		end