dbri: move dereference after check for NULL

We accidentally introduced a dereference before the NULL check in
xmit_descs() as part of silencing a GCC warning.

Fixes: 16f4605 ("dbri: Fix compiler warning")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

sound/sparc/dbri.c

@@ -1702,14 +1702,15 @@ interrupts are disabled.
 static void xmit_descs(struct snd_dbri *dbri)
 {
 	struct dbri_streaminfo *info;
-	u32 dvma_addr = (u32)dbri->dma_dvma;
+	u32 dvma_addr;
 	s32 *cmd;
 	unsigned long flags;
 	int first_td;
 
 	if (dbri == NULL)
 		return;		/* Disabled */
 
+	dvma_addr = (u32)dbri->dma_dvma;
 	info = &dbri->stream_info[DBRI_REC];
 	spin_lock_irqsave(&dbri->lock, flags);