ALSA: emu10k1: Go back and simplify with snd_ctl_find_id()

Now that snd_ctl_find_id() takes the locking itself, we can get rid of
the messy locking in the caller side in snd_emu10k1_verify_controls().

Link: https://lore.kernel.org/r/20230718141304.1032-12-tiwai@suse.de


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