Fix minor issue in hackfest_multivdu introduced with feature 11001

Change-Id: Ib27c2317d20b4c45fa500d0807c7deb106036dd6
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>

robot-systest/testsuite/hackfest_multivdu.robot

@@ -87,7 +87,7 @@ Test SSH Access
     [Documentation]   Check that the VNF is accessible via SSH in its mgmt IP address.
     ${status}   ${message}=   Run Keyword And Ignore Error   Variable Should Exist   ${PRIVATEKEY}
     Log   ${status},${message}
-    IF   ${status} == "FAIL"   Set Global Variable   ${PRIVATEKEY}   ${EMPTY}
+    IF   "${status}" == "FAIL"   Set Global Variable   ${PRIVATEKEY}   ${EMPTY}
     Test SSH Connection   ${VNF_IP_ADDR}   ${USERNAME}   ${PASSWORD}   ${PRIVATEKEY}
 
 Delete NS Instance Test