ALSA: ISA: Remove superfluous *_set_drvdata(NULL) calls

Similarly like the previous commit for PCI drivers, remove
dev_set_drvdata(NULL) and pnp_set_drvdata(NULL) calls in ISA drivers
now.

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

sound/isa/galaxy/galaxy.c

@@ -623,7 +623,6 @@ error:
 static int snd_galaxy_remove(struct device *dev, unsigned int n)
 {
 	snd_card_free(dev_get_drvdata(dev));
-	dev_set_drvdata(dev, NULL);
 	return 0;
 }