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/common/recipes-phosphor/flash/openpower-software-manager/obmc-flash-bios-ubiumount-rw@.service b/common/recipes-phosphor/flash/openpower-software-manager/obmc-flash-bios-ubiumount-rw@.service
index 84fd523..c0ea8e6 100644
--- a/common/recipes-phosphor/flash/openpower-software-manager/obmc-flash-bios-ubiumount-rw@.service
+++ b/common/recipes-phosphor/flash/openpower-software-manager/obmc-flash-bios-ubiumount-rw@.service
@@ -6,4 +6,5 @@
 [Service]
 Type=oneshot
 RemainAfterExit=no
-ExecStart={sbindir}/obmc-flash-bios ubiumount pnor-rw-%i
+ExecStart=/usr/bin/env obmc-flash-bios ubiumount pnor-rw-%i
+SyslogIdentifier=obmc-flash-bios