Replace yaml.load() with yaml.safe_load()

Yaml.load() return Python object may be dangerous if
you receive a YAML document from an untrusted source
such as the Internet. The function yaml.safe_load()
limits this ability to simple Python objects like
integers or lists.

Reference:
https://security.openstack.org/guidelines/dg_avoid-dangerous-input-parsing-libraries.html

Change-Id: I11d34b8235781b7faaeddee0bd658ee9f7ed4297

cinder/tests/unit/volume/drivers/dell_emc/vnx/utils.py

@@ -34,7 +34,7 @@ def load_yaml(file_name):
     yaml_file = '{}/{}'.format(path.dirname(
         path.abspath(__file__)), file_name)
     with open(yaml_file) as f:
-        res = yaml.load(f)
+        res = yaml.safe_load(f)
     return res