bluetooth-device: Add safe guard against BT streaming irregularities.

bluetooth-device: Add safe guard against BT streaming irregularities.

Some bad quality BT-headsets block bluez socket sometimes for hundreds
of milliseconds, especially when changing mode. When the module tries
catch up the lost time it may SBC encode up to half a second of audio
without yielding. On slow machine this may cause maximum RT time slice
to be exceeded. Cleaned out the minor fix that slipped into first version
of the patch.