ALSA: emu10k1: add Audigy 5/Rx

The Audigy 5/Rx is essentially an Audigy 4 behind a PLX PCIe-
bridge with an additional TOSLINK output.

Signed-off-by: Michael Gernoth <michael@gernoth.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>