ALSA: usb: fix usb build error when PM is not enabled

Fix build errors when CONFIG_PM is not enabled:

sound/usb/card.c:629: error: 'usb_audio_suspend' undeclared here (not in a function)
sound/usb/card.c:630: error: 'usb_audio_resume' undeclared here (not in a function)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 0bd62a1aa4f..da1346bd485 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -606,6 +606,9 @@ static int usb_audio_resume(struct usb_interface *intf)
 
         return 0;
 }
+#else
+#define usb_audio_suspend       NULL
+#define usb_audio_resume        NULL
 #endif          /* CONFIG_PM */
 
 static struct usb_device_id usb_audio_ids [] = {