Only clear sync error map on success

We don't want to clear the error map unless there was a successful
sync.  Otherwise, the device will attempt a sync evert 15 seconds
This is the first part of the fix for bug 7567773

This is a cherry-pick of:
https://googleplex-android-review.googlesource.com/#/c/254063/

Change-Id: Ibaf009855c174a2377b0dbde4b5c7bfadb3db4cf
1 file changed