ASoC: simple_card: Show if link is unidirectional

It is handy to know whether the link has playback-only/capture-only flags
when debugging.

Signed-off-by: Stephen Gordon <gordoste@iinet.net.au>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/20250106050659.57924-3-gordoste@iinet.net.au


Signed-off-by: Mark Brown <broonie@kernel.org>