wspoon: Unhardcode cooling type gpio keys device

Use the udev created symlink given the forthcoming introduction
of additional input devices (gpio-keys-polled) and the non-deterministic
probe order that comes along with that.

Change-Id: I0f0ffa96adb958be0c1835ccb1a1e73d5378de03
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/phosphor-fan%/obmc/phosphor-fan/phosphor-cooling-type-0.conf b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/phosphor-fan%/obmc/phosphor-fan/phosphor-cooling-type-0.conf
index 334ded0..e5e8f43 100644
--- a/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/phosphor-fan%/obmc/phosphor-fan/phosphor-cooling-type-0.conf
+++ b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/phosphor-fan%/obmc/phosphor-fan/phosphor-cooling-type-0.conf
@@ -1,6 +1,6 @@
 OBJPATH="--path=/system/chassis"
 AIR="--air"
 WATER=""
-DEVICE="--dev=/dev/input/event0"
+DEVICE="--dev=/dev/input/by-path/platform-gpio-keys-event"
 CODE="--event=13"