Adds the PCI ID for X-Fi cards sold under the Platnum and XtremeMusic names

Before: snd_ctxfi 0000:05:05.0: chip 20K1 model Unknown (1102:0021) is found
After: snd_ctxfi 0000:05:05.0: chip 20K1 model SB046x (1102:0021) is found

[ This is only about defining the model name string, and the rest is
  handled just like before, as a default unknown device. 
  Edward confirmed that the stuff has been working fine -- tiwai ]
Signed-off-by: Edward Matijevic <motolav@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/cae7d1a4-8bd9-7dfe-7427-db7e766f7272@gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de>