ALSA: emu10k1: fix SNDRV_EMU10K1_IOCTL_SINGLE_STEP

ALSA: emu10k1: fix SNDRV_EMU10K1_IOCTL_SINGLE_STEP

- Use correct address limit for Audigy
- Use the right constant to actually make a step on Audigy
- Don't store *_DBG_STEP and the address in emu->fx8010.dbg, as
  otherwise unrelated operations would make steps, too

This is untested. as10k1 was never ported to Audigy anyway.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230422161021.1144004-1-oswald.buddenhagen@gmx.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>