Fix incorrect host time after setting BMC time in NTP/Split

The time tests find an issue that after NTP/BMC is changed to
NTP/Split, setting BMC time will cause host time change.

The root cause is that it fails to set BMC time (which is expected)
but still invokes notifyBmcTimeChange(), which cause host to
re-calculate the offset.

The fix is to not invoke notifyBmcTimeChange() on failure to set BMC
time.

Change-Id: Id13b5fa8ba7def764eab8afad23661f9b0be37ce
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/bmc_epoch.cpp b/bmc_epoch.cpp
index bb3872b..8ddb1ef 100644
--- a/bmc_epoch.cpp
+++ b/bmc_epoch.cpp
@@ -112,9 +112,10 @@
     }
 
     auto time = microseconds(value);
-    setTime(time);
-
-    notifyBmcTimeChange(time);
+    if (setTime(time))
+    {
+        notifyBmcTimeChange(time);
+    }
 
     server::EpochTime::elapsed(value);
     return value;