Enable BMC patching from the /usr/local path

This commit enables patches from the /usr/local path by replacing
absolute paths to /usr/sbin or /usr/bin in every service file with
"/usr/bin/env ". Additionally, SyslogIdentifier is added to each
file to ensure that journal entries are still distinct.

In two cases, service files also had to change due to references
to ${{PATH}}, which doesn't work with /usr/bin/env. These
references - and the corresponding definitions - were changed to
${{DEVPATH}}.

Resolves openbmc/openbmc#2149

Change-Id: I12c5c6e5101eef6820b985a563313836250ff2c7
Signed-off-by: Michael Tritz <mtritz@us.ibm.com>
diff --git a/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-reset-fan-watchdog.service b/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-reset-fan-watchdog.service
index 23c1fca..e0ef0ae 100644
--- a/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-reset-fan-watchdog.service
+++ b/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-reset-fan-watchdog.service
@@ -8,4 +8,5 @@
 Type=oneshot
 RemainAfterExit=yes
 EnvironmentFile={envfiledir}/obmc/witherspoon-fan-watchdog/reset-fan-watchdog.conf
-ExecStart={sbindir}/phosphor-gpio-util -p ${{GPIO_PATH}} -g ${{GPIO}} -a ${{ACTION}} -d ${{DELAY}}
+ExecStart=/usr/bin/env phosphor-gpio-util -p ${{GPIO_PATH}} -g ${{GPIO}} -a ${{ACTION}} -d ${{DELAY}}
+SyslogIdentifier=phosphor-gpio-util