ALSA: pcm: Harden the spk_alloc assumption check

ALSA: pcm: Harden the spk_alloc assumption check

If the parsed ELD has spk_alloc=0, it currently assigns the parsed ELD
spk_alloc to 0xffff. However, we should also check if there is at least
one SAD (Short audio descriptor) to enforce the assumption, as ELD
without any sad_count, is usually considered invalid for e.g. in
commit ce9778b7a0272("ALSA: hda/hdmi: Consider ELD is invalid when no
SAD is present").

Signed-off-by: Umang Jain <uajain@igalia.com>
Link: https://patch.msgid.link/20251120141757.901505-1-uajain@igalia.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>