Documentation: sound: Fix trailing whitespaces

Remove trailing whitespace from sound/hd-audio/notes as reported by
checkpatch. Removing trailing spaces improves consistency, and
prevents Preventing potential merge conflicts due to whitespace
differences. maintain a cleaner and more professional codebase.
Signed-off-by: Abhinav Saxena <xandfury@gmail.com>
Link: https://lore.kernel.org/r/20240515034103.1010269-1-xandfury@gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de>