ALSA: core: Fix possible NULL dereference caused by kunit_kzalloc()

In the Linux kernel, the following vulnerability has been resolved: ALSA: core: Fix possible NULL dereference caused by kunit_kzalloc() kunit_kzalloc() may return a NULL pointer, dereferencing it without NULL check may lead to NULL dereference. Add NULL checks for all the kunit_kzalloc() in sound_kunit.c