ASoC: test-component: fix null pointer dereference.

Dereferncing of_id pointer will result in exception in current
implementation since of_match_device() will assign it to NULL.
Adding NULL check for protection.

Signed-off-by: Ameer Hamza <amhamza.mgc@gmail.com>
Link: https://lore.kernel.org/r/20211207142309.222820-1-amhamza.mgc@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>