ALSA: hda/hdmi: Remove some dead code

These snd_BUG_ON() can never trigger, so just remove them to save a few
LoC.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/91a31341f32d493bcc6c4515178ce0755ac1aa70.1681710069.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Takashi Iwai <tiwai@suse.de>