[dvsim] Use a more pythonic test for empty lists

Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/util/dvsim/Deploy.py b/util/dvsim/Deploy.py
index c4675ef..fef2982 100644
--- a/util/dvsim/Deploy.py
+++ b/util/dvsim/Deploy.py
@@ -526,7 +526,7 @@
 
     @staticmethod
     def get_seed():
-        if RunTest.seeds == []:
+        if not RunTest.seeds:
             for i in range(1000):
                 seed = random.getrandbits(32)
                 RunTest.seeds.append(seed)