IPMI SOL activate verification logic update

The current logic checks for "Petitboot" on the IPMI SOL output. Most
of the time we see the SOL output wraps up during the boot in progress
and it couldn't find the string when looked up.

The new logic breaks down into two pieces. First, it checks for the
welcome message on the SOL as the marker for host boot in progress and
secondly, checks for the "ISTEP".

This two prong approach achieves:
1. SOL active verification is faster and
2. Better strings validation SOL message.

Resolves  openbmc/openbmc-test-automation#1019

Change-Id: I94e8c64a70bf20dd34d6669c79cfa4db2b2550f2
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/tests/ipmi/test_sol.robot b/tests/ipmi/test_sol.robot
index 3e41680..ded136d 100644
--- a/tests/ipmi/test_sol.robot
+++ b/tests/ipmi/test_sol.robot
@@ -125,8 +125,11 @@
     Initiate Host Boot Via External IPMI  wait=${0}
 
     Activate SOL Via IPMI
-    Wait Until Keyword Succeeds  10 mins  30 secs
-    ...  Check IPMI SOL Output Content  Petitboot
+    Wait Until Keyword Succeeds  3 mins  30 secs
+    ...  Check IPMI SOL Output Content  Welcome to Hostboot hostboot
+
+    Wait Until Keyword Succeeds  3 mins  30 secs
+    ...  Check IPMI SOL Output Content  ISTEP
 
 Verify Deactivate Non Existing SOL
     [Documentation]  Verify deactivate non existing SOL session.