Revert "[rbp/omxplayer] Support both analogue and hdmi audio"

This reverts commit 7813a29b3289ab29b039041e1980b38663db0225.
[rbp/omxplayer] Fix uninitialised variable that can lose audio packet

The uninitialised variable meant the first run through Decode goes through the non-passthrough path (when passthrough)
and so doesn't get correctly submitted and is discarded