ALSA: usb: make snd_pcm_hardware const

Make this const as it is only used in a copy operation.
Done using Coccinelle.
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

@@ -857,7 +857,7 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 	return ret;
 }
 
-static struct snd_pcm_hardware snd_usb_hardware =
+static const struct snd_pcm_hardware snd_usb_hardware =
 {
 	.info =			SNDRV_PCM_INFO_MMAP |
 				SNDRV_PCM_INFO_MMAP_VALID |