Fix ec2_asg_facts when `name` parameter is None

Closes #3021

cloud/amazon/ec2_asg_facts.py

@@ -299,7 +299,11 @@ def find_asgs(conn, module, name=None, tags=None):
         module.fail_json(msg=e.message, **camel_dict_to_snake_dict(e.response))
 
     matched_asgs = []
-    name_prog = re.compile(r'^' + name)
+
+    if name is not None:
+        # if the user didn't specify a name
+        name_prog = re.compile(r'^' + name)
+
     for asg in asgs['AutoScalingGroups']:
         if name:
             matched_name = name_prog.search(asg['AutoScalingGroupName'])