meta-openpower: fix logging in first-boot-set-*

Makes the showing of the warnings  in the first-boot-set-mac.sh and
first-boot-set-hostname.sh are same

If the script runs manually the warning messages are shown on STDERR.
If the script runs as a systemd unit the warning messages  are shown in
a system journal.

(From meta-openpower rev: f80fbdb15330f694e4f80992470605d46b998efd)

Change-Id: I44bdc5ff3ad6bee3bcae2d2a0e574cac3353cdde
Signed-off-by: Alexander Filippov <a.filippov@yadro.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-openpower/recipes-phosphor/network/first-boot-set-hostname/first-boot-set-hostname.sh b/meta-openpower/recipes-phosphor/network/first-boot-set-hostname/first-boot-set-hostname.sh
index 5415237..cf67f8b 100644
--- a/meta-openpower/recipes-phosphor/network/first-boot-set-hostname/first-boot-set-hostname.sh
+++ b/meta-openpower/recipes-phosphor/network/first-boot-set-hostname/first-boot-set-hostname.sh
@@ -1,7 +1,11 @@
 #!/bin/sh -eu
 
 show_error() {
-    echo "$@" >&2
+    if [ -n "${JOURNAL_STREAM-}" ]; then
+        echo "$@" | systemd-cat -t first-boot-set-hostname -p emerg
+    else
+        echo "$@" >&2
+    fi
 }
 
 sync_hostname() {
@@ -26,7 +30,7 @@
                                 ${BMC_ITEM_PATH} 2>/dev/null || true)
 
     if [[ -z "${BMC_ITEM_SERVICE}" ]]; then
-        echo "No BMC item found in the Inventory. Is VPD EEPROM empty?" >&2
+        show_error "No BMC item found in the Inventory. Is VPD EEPROM empty?"
         return
     fi
 
@@ -43,4 +47,3 @@
 [ "$(hostname)" = "{MACHINE}" ] && sync_hostname
 
 systemctl disable first-boot-set-hostname.service
-