usb: don't use 'Yoda conditions'

imitate nearby code about using '!value' or 'value == NULL'

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

1 files changed, 1 insertions, 1 deletions

diff --git a/hw/usb/dev-audio.c b/hw/usb/dev-audio.c
index bfebfe90f3..7b9957b3c3 100644
--- a/hw/usb/dev-audio.c
+++ b/hw/usb/dev-audio.c
@@ -371,7 +371,7 @@ static void output_callback(void *opaque, int avail)
             return;
         }
         data = streambuf_get(&s->out.buf);
-        if (NULL == data) {
+        if (!data) {
             return;
         }
         AUD_write(s->out.voice, data, USBAUDIO_PACKET_SIZE);