cras_alsa_io: Fix dereference of null pointer

Since ain from get_active_input could be NULL, we should do nullity
check before accessing ain->base.type.

BUG=b:170096536
TEST=scan-build make check

Change-Id: I658f7a2568cd9b97e2c3cec9b936920a38567927
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/2452193
Tested-by: Chih-Yang Hsia <paulhsia@chromium.org>
Commit-Queue: Chih-Yang Hsia <paulhsia@chromium.org>
Reviewed-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
1 file changed