expr: Add Hash to the expr type

Add the Hash type to the expr read parser.

Signed-off-by: Rafael Campos <methril@gmail.com>

expr/expr.go

@@ -134,6 +134,8 @@ func exprsFromBytes(fam byte, ad *netlink.AttributeDecoder, b []byte) ([]Any, er
 					e = &Reject{}
 				case "masq":
 					e = &Masq{}
+				case "hash":
+					e = &Hash{}
 				}
 				if e == nil {
 					// TODO: introduce an opaque expression type so that users know