ALSA: aloop: Introduce a function to get if access is interleaved mode

ALSA: aloop: Introduce a function to get if access is interleaved mode

There's a use case that playback stream of a loopback cable works on
RW_INTERLEAVED mode while capture stream works on MMAP_INTERLEAVED mode:

aplay -Dhw:Loopback,0,0 S32_48K_2ch.wav;
arecord -Dplughw:Loopback,1,0 -fS32_LE -r16000 -c2 cap.wav;

The plug plugin handles only slave PCM support MMAP mode. Not only plug
plugin but also other plugins like direct plugins(dmix/dsnoop/dshare)
work on MMAP access mode. In this case capture stream is the slave
PCM works on MMAP_INTERLEAVED mode. However loopback_check_format()
rejects this access setting and return:

arecord: pcm_read:2240: read error: Input/output error

To fix it a function called is_access_interleaved() is introduced to
get if access is interleaved mode. If both access of capture stream and
playback stream is interleaved mode loopback_check_format() will allow
this kind of access setting.

Fixes: 462494565c27 ("ALSA: aloop: Add support for the non-interleaved access mode")
Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
Link: https://lore.kernel.org/r/20240111025219.2678764-1-chancel.liu@nxp.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>