[ALSA] emu10k1 - EMU 1212 with 16 capture channels

* adding 8 more 32-bit capture channels (total of 16) for emu1010 cards
* adding some code comments and card details description

Signed-off-by: Pavel Hofman <dustin@seznam.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>