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

Fixes: 3e39acf5 ("ALSA: core: Add sound core KUnit test")
Signed-off-by: Zichen Xie <zichenxie0106@gmail.com>
Link: https://patch.msgid.link/20241126192448.12645-1-zichenxie0106@gmail.com


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