ALSA: emu10k1: un-hardcode E-MU mixer control callbacks somewhat

ALSA: emu10k1: un-hardcode E-MU mixer control callbacks somewhat

Instead of hard-coding the card-specific arrays and their sizes in each
function, use a more data-driven approach.

As a drive-by, also hide the unavailable I2S input destinations on the
1616 cardbus card.

Also as a drive-by, use more assignments at variable declaration for
brevity. This also removes the pointless masking of kctl.private_value.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230516093612.3536508-5-oswald.buddenhagen@gmx.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>