wspoon: Fix max31785 hwmon startup

The max31785 hwmon instance fails to start after a systemd patch was
removed to handle special characters in the device paths. This uses
`systemd-escape` to escape and unescape the device path when the udev
rule triggers the max31785 hwmon startup script.

Resolves openbmc/openbmc#3443

Change-Id: I4a504aaae0b0692e8838f66f8d7c37415e9566d0
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/meta-witherspoon/recipes-phosphor/sensors/phosphor-hwmon/max31785-hwmon-helper@.service b/meta-witherspoon/recipes-phosphor/sensors/phosphor-hwmon/max31785-hwmon-helper@.service
index 98b5541..c7ed6f1 100644
--- a/meta-witherspoon/recipes-phosphor/sensors/phosphor-hwmon/max31785-hwmon-helper@.service
+++ b/meta-witherspoon/recipes-phosphor/sensors/phosphor-hwmon/max31785-hwmon-helper@.service
@@ -5,5 +5,5 @@
 
 [Service]
 Type=oneshot
-ExecStart=/usr/bin/env start_max31785_hwmon.sh %I
+ExecStart=/usr/bin/env start_max31785_hwmon.sh %i
 SyslogIdentifier=max31785-hwmon-helper