Add test case for invalid static IPv6

    Changes:
        Add a new test case for invalid static IPv6

    Tested:
        Ran and Tested on BMC Environment

Change-Id: If6f8b2e4ebd7534c1f7b911ed353fd2846ea115c
Signed-off-by: Sweta Potthuri <spotthur@in.ibm.com>
diff --git a/lib/external_intf/vmi_utils.robot b/lib/external_intf/vmi_utils.robot
index 21b7c22..836e9c8 100644
--- a/lib/external_intf/vmi_utils.robot
+++ b/lib/external_intf/vmi_utils.robot
@@ -31,6 +31,7 @@
 
 ${wait_time}              40s
 ${ethernet_interface}     eth0
+${ipv4_hexword_addr}      10.5.5.6:1A:1B:1C:1D:1E:1F
 
 *** Keywords ***