test: add audio_time

test: add audio_time

Simple test to create playback and capture streams, and
check elapsed time vs. sample counts reported by driver.
This should be helpful for driver developers and anyone
interested in system/audio time drift.

tested only on HDAudio

[added Makefile.am change by tiwai]

TODO:
- make period configurable
- better output messages
- support for wall clock when it's in the mainline

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>