The functions kfree(), release_firmware() and snd_util_memhdr_free() test
whether their argument is NULL and then return immediately. Thus the test
around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>