meta-quanta: powerctrl: use dts for gpiochip

The device-tree path should be used to select the
gpio chip.

Change-Id: I5f5bb6b5ddac1f9102249795130434c4b61201f6
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/meta-q71l/recipes-phosphor/quanta-powerctrl/files/poweroff.sh b/meta-q71l/recipes-phosphor/quanta-powerctrl/files/poweroff.sh
index e429131..8e0dae3 100755
--- a/meta-q71l/recipes-phosphor/quanta-powerctrl/files/poweroff.sh
+++ b/meta-q71l/recipes-phosphor/quanta-powerctrl/files/poweroff.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-GPIO_BASE=$(cat /sys/class/gpio/gpiochip*/base)
+GPIO_BASE=$(cat /sys/devices/platform/ahb/ahb:apb/1e780000.gpio/gpio/*/base)
 GPIO_NUM=$(($GPIO_BASE + 24 + 3))
 
 echo 1 > /sys/class/gpio/gpio${GPIO_NUM}/value