Revert "Drop buffers when latency gets larger than buffer size."

We cannot use fEventLatency to compare with buffer size, it includes
the whole downstream latency. Nodes have to do the run-mode adjustment
themselves, based on their internal latency. Unfortunately that is not
known to BMediaEventLooper.

This reverts commit bc1fb70f5ac3cea1c3c04ba529b6f67dca2863ba.