Fix pylint warning on regex string

Change-Id: I1a5eb17709d0e01ab26dc8c8fe727f4f7a7da283
diff --git a/drivers/Dummy.py b/drivers/Dummy.py
index 66a35b0..41f36af 100644
--- a/drivers/Dummy.py
+++ b/drivers/Dummy.py
@@ -208,7 +208,7 @@
         except:
             # Create data here
             self._dummy_vlans = {1: 'DEFAULT'}
-            match = re.match('dummy-(\d+)', self.hostname)
+            match = re.match(r'dummy-(\d+)', self.hostname)
             if match:
                 num_ports = int(match.group(1))
             else: