Remove dead code written for PHP 5.2
diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index df7e084..56fdf32 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -386,7 +386,7 @@
 	 */
 	protected function _trans_begin()
 	{
-		$this->commit_mode = is_php('5.3.2') ? OCI_NO_AUTO_COMMIT : OCI_DEFAULT;
+		$this->commit_mode = OCI_NO_AUTO_COMMIT;
 		return TRUE;
 	}