drivers/net/ethernet/ti/davinci_cpdma.c: Remove potential NULL dereference

If the NULL test is necessary, the initialization involving a dereference of
the tested value should be moved after the NULL test.

The sematic patch that fixes this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
type T;
expression E;
identifier i,fld;
statement S;
@@

- T i = E->fld;
+ T i;
  ... when != E
      when != i
  if (E == NULL) S
+ i = E->fld;
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/davinci_cpdma.c

@@ -538,11 +538,12 @@ EXPORT_SYMBOL_GPL(cpdma_chan_create);
 
 int cpdma_chan_destroy(struct cpdma_chan *chan)
 {
-	struct cpdma_ctlr *ctlr = chan->ctlr;
+	struct cpdma_ctlr *ctlr;
 	unsigned long flags;
 
 	if (!chan)
 		return -EINVAL;
+	ctlr = chan->ctlr;
 
 	spin_lock_irqsave(&ctlr->lock, flags);
 	if (chan->state != CPDMA_STATE_IDLE)