ALSA: pcm.h: add for_each_pcm_streams()

ALSA code has SNDRV_PCM_STREAM_PLAYBACK/CAPTURE everywhere.
Having for_each_xxxx macro is useful.
This patch adds for_each_pcm_streams() for it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/874kvpbotq.wl-kuninori.morimoto.gx@renesas.com


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