ASoC: samsung: i2s: Fix DAPM routes for capture stream

This patch sets missing stream_name of capture part of the DAI driver
so we can define DAPM routing properly also for the capture stream.

While at it "Playback" suffix is added to the playback stream names
to clearly identify playback/capture.

Together with related dts patch this fixes NULL pointer dereference
when opening ALSA device for recording on Odroid XU3.

Fixes: 64aba9bc ("ASoC: samsung: i2s: Add widgets and routes for DPCM support")
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>