ffdc: Convert telnet return data to ASCII string.

telnetlib return data as a binary list.
Convert return data to ASCII string for processing.

Test:
- Regression test to telnet servers.

Signed-off-by: Peter D  Phan <peterp@us.ibm.com>
Change-Id: I3ed066556a026370ea2e4a641d64bea90f9c5124
diff --git a/ffdc/lib/telnet_utility.py b/ffdc/lib/telnet_utility.py
index e2a3adf..4ffa98f 100644
--- a/ffdc/lib/telnet_utility.py
+++ b/ffdc/lib/telnet_utility.py
@@ -125,5 +125,5 @@
 
             logging.error("\t\t ERROR %s " % msg)
 
-        # Return binary data.
-        return local_buffer
+        # Return ASCII string data with ending PROMPT stripped
+        return local_buffer.decode('ascii', 'ignore').replace('$ ', '\n')