Remove confusing comment in common/compute.py

This commit removes a confusing comment. This "l.58" indicated that
around line 126 - `if multiple_create_request:` condition, originally.
(The condition has been modified from the original one, though.) And, we
shouldn't fix it to 'l.126' because it isn't stable.

Change-Id: Iad059ce8a97da544948e5383461a4cc480067992
diff --git a/tempest/common/compute.py b/tempest/common/compute.py
index f0fceb3..638ad9b 100644
--- a/tempest/common/compute.py
+++ b/tempest/common/compute.py
@@ -229,7 +229,7 @@
                     clients.servers_client, server['id'], wait_until)
 
                 # Multiple validatable servers are not supported for now. Their
-                # creation will fail with the condition above (l.58).
+                # creation will fail with the condition above.
                 if CONF.validation.run_validation and validatable:
                     if CONF.validation.connect_method == 'floating':
                         _setup_validation_fip()