ASoC: wcd9320: Avoid NULL pointer access

It is possible that taiko private data will
be accessed without creating memory when
sound card is not registered. Avoid kernel
crash by checking it for NULL and return without
access.

Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>