ALSA: ppc: keywest: remove outdated comment

The I2C attach_adapter callback is gone. Remove this reference.

Signed-off-by: Wolfram Sang <wsa@kernel.org>
Link: https://lore.kernel.org/r/20210310193227.333140-1-wsa@kernel.org


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