ALSA: usb-audio: remove assignment from if condition

Following general kernel style.

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 3d3e8d1..be5c7c2 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -479,7 +479,8 @@
 		subs->data_endpoint->sync_master = subs->sync_endpoint;
 	}
 
-	if ((err = snd_usb_init_pitch(subs->stream->chip, fmt->iface, alts, fmt)) < 0)
+	err = snd_usb_init_pitch(subs->stream->chip, fmt->iface, alts, fmt);
+	if (err < 0)
 		return err;
 
 	subs->cur_audiofmt = fmt;