[ci skip] Remove some redundant code from DB_forge
diff --git a/system/database/DB_forge.php b/system/database/DB_forge.php
index d2302b2..1546e40 100644
--- a/system/database/DB_forge.php
+++ b/system/database/DB_forge.php
@@ -780,10 +780,6 @@
 					case 'ENUM':
 					case 'SET':
 						$attributes['CONSTRAINT'] = $this->db->escape($attributes['CONSTRAINT']);
-						$field['length'] = is_array($attributes['CONSTRAINT'])
-							? "(".implode(",", $attributes['CONSTRAINT']).")"
-							: '('.$attributes['CONSTRAINT'].')';
-						break;
 					default:
 						$field['length'] = is_array($attributes['CONSTRAINT'])
 							? '('.implode(',', $attributes['CONSTRAINT']).')'