ALSA: ice1724: Fix blocking open for independent surround PCMs

The independent surround playback open path rejects a substream when the
matching PDMA channel is reserved by the multi-channel PDMA0 stream. It
currently returns -EBUSY for that case, although the driver has carried a
FIXME noting that blocking mode is not handled properly.

ALSA PCM open waits and retries only when the low-level open callback
returns -EAGAIN. Returning -EBUSY therefore makes blocking opens fail
immediately, the same as nonblocking opens.

Return -EAGAIN for the temporary PDMA0 reservation conflict. The PCM core
continues to report -EBUSY for O_NONBLOCK callers, while blocking callers
sleep and retry.

Also wake the independent surround PCM wait queue when hw_free releases a
PDMA reservation. The reservation can be released by the pro PCM, while
waiters are sleeping on the independent surround PCM, so waking the current
substream PCM is not sufficient for this cross-PCM reservation.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260518-ice1724-blocking-open-v1-1-1bfa3e5aa7cf@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

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