pcm: set error code at failure path
pcm: set error code at failure path

This commit fixes below compiler warnings.

pcm_hw.c: In function ‘_snd_pcm_hw_open’:
pcm_hw.c:1816:16: warning: ‘err’ may be used uninitialized in this function [-Wmaybe-uninitialized]
         return err;
                ^

Signed-off-by: Takashi Sakamoto <d5ec7d0cd8074757a1f5eb708bc105c3065a65ea@sakamocchi.jp>
Signed-off-by: Takashi Iwai <4596b3305151c7ee743192a95d394341e3d3b644@suse.de>

tiwai/alsa-lib,alsa-project/alsa-lib,takaswie/alsa-lib,zedongchen/alsa-lib,tiwai/alsa-lib,alsa-project/alsa-lib,takaswie/alsa-lib,takaswie/alsa-lib,zedongchen/alsa-lib,tiwai/alsa-lib,takaswie/alsa-lib,alsa-project/alsa-lib,tiwai/alsa-lib,alsa-project/alsa-lib,zedongchen/alsa-lib,zedongchen/alsa-lib,takaswie/alsa-lib,zedongchen/alsa-lib