ALSA: emu10k1: Drop superfluous id-uniquification behavior

The emu10k1 driver tries to create a unique id string by itself when
it's copied from the card list, but it's rather superfluous, as the
same thing will be done in ALSA core side at the card registration.
Let's drop the code.  This allows us removing snd_cards export.

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