ALSA: sb8: Add a comment note regarding an unused pointer

The field "fm_res" of "struct snd_sb8" is never used/dereferenced
throughout the sb8.c code. Therefore there is no need for any null value
check after the "request_region()".

Add a comment note to make developers know about this and prevent any
"NULL check" patches on this part of code.

Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Atul Gopinathan <atulgopinathan@gmail.com>
Link: https://lore.kernel.org/r/20210503115736.2104747-36-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sound/isa/sb/sb8.c

@@ -93,7 +93,11 @@ static int snd_sb8_probe(struct device *pdev, unsigned int dev)
 	acard = card->private_data;
 	card->private_free = snd_sb8_free;
 
-	/* block the 0x388 port to avoid PnP conflicts */
+	/*
+	 * Block the 0x388 port to avoid PnP conflicts.
+	 * No need to check this value after request_region,
+	 * as we never do anything with it.
+	 */
 	acard->fm_res = request_region(0x388, 4, "SoundBlaster FM");
 
 	if (port[dev] != SNDRV_AUTO_PORT) {