dpcm_xxx flags are no longer needed.

We need to use xxx_only flags instead if needed, but
snd_soc_dai_link_set_capabilities() user adds dpcm_xxx if playback/capture
were available. Thus converting dpcm_xxx to xxx_only is not needed.
Just remove it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://patch.msgid.link/87r0aiaahh.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>