python: fix flake8 warnings

./python/netlink/route/tc.py:599:37: C408 Unnecessary dict call - rewrite as a literal.
./python/netlink/route/tc.py:610:16: C416 Unnecessary list comprehension - rewrite using list().
./python/netlink/util.py:106:47: C408 Unnecessary dict call - rewrite as a literal.

python/netlink/route/tc.py

@@ -596,7 +596,7 @@ def get_class(ifindex, parent, handle=None):
 
 def get_cls(ifindex, parent, handle=None):
 
-    chain = _cls_cache.get(ifindex, dict())
+    chain = _cls_cache.get(ifindex, {})
 
     try:
         cache = chain[parent]
@@ -607,6 +607,6 @@ def get_cls(ifindex, parent, handle=None):
     cache.refill()
 
     if handle is None:
-        return [cls for cls in cache]
+        return list(cache)
 
     return [cls for cls in cache if cls.handle == handle]

python/netlink/util.py

@@ -103,7 +103,7 @@ def _nlattr(self, key):
         if not isinstance(value, property):
             raise ValueError("Invalid formatting string {0}".format(key))
 
-        d = getattr(value.fget, "formatinfo", dict())
+        d = getattr(value.fget, "formatinfo", {})
 
         # value = value.fget() is exactly the same
         value = getattr(self._obj, key)