Remove old pep8 ignores that are no longer necessary

Change-Id: Ia690ea0a284f1e1cfe7e223613acdb30e40a9980
diff --git a/tox.ini b/tox.ini
index 921fee1..ee31c64 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,10 +25,8 @@
 commands = oslo_debug_helper {posargs}
 
 [flake8]
-# E123, E125 skipped as they are invalid PEP-8.
 # W504 line break after binary operator
-
 show-source = True
-ignore = E123,E125,W504
+ignore = W504
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build