ALSA: sb: Deletion of unnecessary checks before two function calls

The functions release_and_free_resource() 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: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>