ALSA: hda: provide default bus io ops extended hdac

A typical io ops use simple io accessors which can be common for most
drivers, so provide a default ops which will be used if driver doesn't
provide one

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>