ANDROID: usb: gadget: f_audio_source: disable the CPU C-states upon playback

Due to the issue with the isoc transfers being interrupted
by the CPU going into the idle state, the C-states will be
disabled for the playback time.

Change-Id: If4e52673606923d7e33a1d1dbe0192b8ad24f78c
Signed-off-by: Konrad Leszczynski <konrad.leszczynski@intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>