Tempest: fix a typo

allocaion => allocation

TrivialFix

Change-Id: I5e581858fcf4aa43fa72757ba6630dc80ed1dc84
diff --git a/neutron/tests/tempest/api/base.py b/neutron/tests/tempest/api/base.py
index 45e12f0..1d804ee 100644
--- a/neutron/tests/tempest/api/base.py
+++ b/neutron/tests/tempest/api/base.py
@@ -428,7 +428,7 @@
 
     @classmethod
     def get_unused_ip(cls, net_id, ip_version=None):
-        """Get an unused ip address in a allocaion pool of net"""
+        """Get an unused ip address in a allocation pool of net"""
         body = cls.admin_client.list_ports(network_id=net_id)
         ports = body['ports']
         used_ips = []