Fix for ReadTimeout error while connecting back after warm reset

ReadTimeout is coming as REST login is done just after BMC
becomes pingable after warm reset.

This fix includes:
   - Usage of "Check if BMC is up" keyword to make sure that
      both ping and REST connection to BMC is successful
      after warm reset.

Resolves  openbmc/openbmc-test-automation#301

Change-Id: I10d6cc2fc485e7f2715b5c6b6d0c31dfcb545524
Signed-off-by: Rahul Maheshwari <rahulmaheshwari@in.ibm.com>
diff --git a/lib/utils.robot b/lib/utils.robot
index d4297f8..0ac02f8 100755
--- a/lib/utils.robot
+++ b/lib/utils.robot
@@ -101,7 +101,7 @@
     ...    Fail   msg=warm reset didn't occur
 
     Sleep   ${SYSTEM_SHUTDOWN_TIME}min
-    Wait For Host To Ping   ${OPENBMC_HOST}
+    Check If BMC Is Up
 
 Check OS
     [Documentation]  Attempts to ping the host OS and then checks that the host