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-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-fan-watchdog-monitor@.service b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-fan-watchdog-monitor@.service
index 9eb9697..945561b 100644
--- a/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-fan-watchdog-monitor@.service
+++ b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/fans/witherspoon-fan-watchdog/witherspoon-fan-watchdog-monitor@.service
@@ -6,4 +6,5 @@
 
 [Service]
 Type=oneshot
-ExecStart=/usr/sbin/phosphor-unit-failure-monitor --source %i --target obmc-fan-watchdog-takeover.target --action start
+ExecStart=/usr/bin/env phosphor-unit-failure-monitor --source %i --target obmc-fan-watchdog-takeover.target --action start
+SyslogIdentifier=phosphor-unit-failure-monitor