ALSA: als300: Fix missing chip initialization

The recent code refactoring missed the initialization of the chip
variable as its allocation was moved to card->private_data.
Let's fix it.

Fixes: 21a9314c ("ALSA: als300: Allocate resources with device-managed APIs")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/s5hh7goocid.wl-tiwai@suse.de


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