Delete unused parameters

param:expected_errors is not used in the following code, it is
meaningless, so delete it.

Change-Id: I37b95b750689d87163a595b68a0dbaa9c551c62f
diff --git a/tempest/api/baremetal/admin/base.py b/tempest/api/baremetal/admin/base.py
index f7891dd..2d3f190 100644
--- a/tempest/api/baremetal/admin/base.py
+++ b/tempest/api/baremetal/admin/base.py
@@ -96,7 +96,7 @@
 
     @classmethod
     @creates('chassis')
-    def create_chassis(cls, description=None, expect_errors=False):
+    def create_chassis(cls, description=None):
         """Wrapper utility for creating test chassis.
 
         :param description: A description of the chassis. if not supplied,