ASoC: samsung: i2s: Restore support for the secondary PCM

ASoC: samsung: i2s: Restore support for the secondary PCM

This patch introduces again registration of additional platform device as
we still need it for registering the secondary dmaengine PCM component.

This patch in most part is a revert of changes done in commit
be2c92eb64023e ("ASoC: samsung: i2s: Remove virtual device for secondary DAI")

Change-Id: Ib7a47c83511403b32e04c41edf8148d77481abb3
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>