Update login in systest utility library

Specify which Login to use in utils_os.robot.
Resolves openbmc/openbmc-test-automation#1617

Change-Id: I8ccb79b11c54ab4bb22e205eb0ab89332590d0f1
Signed-off-by: Steven Sombar <ssombar@us.ibm.com>
diff --git a/syslib/utils_os.robot b/syslib/utils_os.robot
index 9c060df..0c99e91 100755
--- a/syslib/utils_os.robot
+++ b/syslib/utils_os.robot
@@ -47,7 +47,7 @@
 
     Ping Host  ${os_host}
     SSHLibrary.Open Connection  ${os_host}  alias=${alias_name}
-    Login  ${os_username}  ${os_password}
+    SSHLibrary.Login  ${os_username}  ${os_password}
 
 
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