pcm: add missing "break" in "switch"

pcm: add missing "break" in "switch"

A missing "break" in procedure snd_pcm_write_mmap() causes
execution of "case SND_PCM_ACCESS_MMAP_NONINTERLEAVED" to
fall through next "default" case of the "switch" statement.
Since "default" handles error cases, the procedure returns
error.

The error fixed by this patch blocks transfer of capture
data from kernel to application. Execution get stuck in
alsa-lib, that discards all received data.

Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>