vdev_id: Fix enclosure_symlinks feature

The vdev_id.conf "enclosure_symlinks" option persistently creates
and maps /dev/by-enclosure symlinks to dynamic /dev/sg* devices.

This patch fixes two issues:

1. The enclosure_symlinks feature was accidentally broken in:

   vdev_id: Support daisy-chained JBODs in multipath mode

2. Even when working, the feature numbered the enclosure
   sequentially rather than by HBA port number.  That meant that
   if a port was down or didn't appear in sysfs, then the
   enclosure_sumlinks numbers would be numbered wrong.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Arshad Hussain <[email protected]>
Signed-off-by: Tony Hutter <[email protected]>
Closes #12660

cmd/vdev_id/vdev_id

@@ -622,8 +622,8 @@ enclosure_handler () {
 	PCI_ID=$(echo "$PCI_ID_LONG" | sed -r 's/^[0-9]+://g')
 
 	# Name our device according to vdev_id.conf (like "L0" or "U1").
-	NAME=$(awk '/channel/{if ($1 == "channel" && $2 == "$PCI_ID" && \
-		$3 == "$PORT_ID") {print ${4}int(count[$4])}; count[$4]++}' $CONFIG)
+	NAME=$(awk "/channel/{if (\$1 == \"channel\" && \$2 == \"$PCI_ID\" && \
+		\$3 == \"$PORT_ID\") {print \$4\$3}}" $CONFIG)
 
 	echo "${NAME}"
 }