Fix SSB TEMP reading 0

From the NM spec, 0 means scanning disabled,
treat this as a read error and not an actual reading.

Tested: Couldn't, my system doesn't read 0

Change-Id: I43e0ee2bd5bdcd1a6386ef745a5b974619193f12
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/src/IpmbSensor.cpp b/src/IpmbSensor.cpp
index d8b0d4f..5658210 100644
--- a/src/IpmbSensor.cpp
+++ b/src/IpmbSensor.cpp
@@ -234,7 +234,14 @@
     switch (readingFormat)
     {
         case (ReadingFormat::byte0):
+            // from node manager app-note, response of 0 means scanning disabled
+            // for get sensor reading command
+            if (data[0] == 0)
+            {
+                return false;
+            }
             resp = data[0];
+
             return true;
         case (ReadingFormat::byte3):
             if (data.size() < 4)