Detect iSCSI in the zpool cmd vdev media script

Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes openzfs#12206

cmd/zpool/zpool.d/media

@@ -4,7 +4,7 @@
 #
 
 if [ "$1" = "-h" ] ; then
-	echo "Show whether a vdev is a file, hdd, or ssd."
+	echo "Show whether a vdev is a file, hdd, ssd, or iscsi."
 	exit
 fi
 
@@ -18,6 +18,13 @@ if [ -b "$VDEV_UPATH" ]; then
 	if [ "$val" = "1" ]; then
 		MEDIA="hdd"
 	fi
+
+	vpd_pg83="/sys/block/$device/device/vpd_pg83"
+	if [ -f "$vpd_pg83" ]; then
+		if grep -q --binary "iqn." "$vpd_pg83"; then
+			MEDIA="iscsi"
+		fi
+	fi
 else
 	if [ -f "$VDEV_UPATH" ]; then
 		MEDIA="file"