ASoC: Add documentation for pcm3060 property out-single-ended

Output of pcm3060 codec may be configured as single-ended or differential

Signed-off-by: Kirill Marinushkin <kmarinushkin@birdec.tech>
Signed-off-by: Mark Brown <broonie@kernel.org>

ASoC: pcm3060: Add codec driver

This commit adds support for TI PCM3060 CODEC.
The technical documentation is available at [1].

[1] http://ti.com/product/pcm3060

Signed-off-by: Kirill Marinushkin <kmarinushkin@birdec.tech>
Cc: Mark Brown <broonie@kernel.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: M R Swami Reddy <mr.swami.reddy@ti.com>
Cc: Vishwas A Deshpande <vishwas.a.deshpande@ti.com>
Cc: Kevin Cernekee <cernekee@chromium.org>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: alsa-devel@alsa-project.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>