Removed driver copy_user(), copy_kernel() and fill_silence() ops.
Removed user space buffer transfer handling mode from playback and capture copy_internal() functions.
The problem arises from pre-buffering performed after ALSA prepare and before ALSA start trigger-
The patch enables the early startup of the audio playback interrupt and disables the cleanup (mute) of the playback buffer.
This issue can be reproduced using the test suite developed to investigate #17 and by removing the (-M) option from aplay in run_test.sh script.
