initfs: update: Consistently add ERROR: and print to stderr

Make sure all error messages start with the tag ERROR.  Also redirect
output to stderr (once case had the file descriptors backwards).

Signed-off-by: Milton Miller <miltonm@us.ibm.com>
diff --git a/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh b/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh
index f0ca989..4249161 100755
--- a/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh
+++ b/meta-phosphor/common/recipes-phosphor/obmc-phosphor-initfs/files/obmc-update.sh
@@ -21,7 +21,7 @@
 
 if grep mtd /proc/mounts
 then
-	echo 1>&2 "Error: A mtd device is mounted."
+	echo 1>&2 "ERROR: A mtd device is mounted."
 	exit 1
 fi
 
@@ -65,6 +65,8 @@
 whitelist=/run/initramfs/whitelist
 image=/run/initramfs/image-
 
+E="ERROR:"
+
 while test "$1" != "${1#-}"
 do
 	case "$1" in
@@ -90,7 +92,7 @@
 		toram=y
 		shift ;;
 	*)
-		echo 2>&1 "Unknown option $1"
+		echo 1>&2 "$E Unknown option $1"
 		exit 1 ;;
 	esac
 done
@@ -126,7 +128,7 @@
 	m=$(findmtd ${f#$image})
 	if test -z "$m"
 	then
-		echo 1>&2  "Unable to find mtd partiton for ${f##*/}."
+		echo 1>&2 "$E Unable to find mtd partiton for ${f##*/}."
 		exit 1
 	fi
 done