usb: musb: ux500_dma: fix potential NULL dereference error

static checker warning: "drivers/usb/musb/ux500_dma.c:335
ux500_dma_controller_start()
         error: potential NULL dereference 'param_array'."

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/musb/ux500_dma.c b/drivers/usb/musb/ux500_dma.c
index 3700e97..9aad00f 100644
--- a/drivers/usb/musb/ux500_dma.c
+++ b/drivers/usb/musb/ux500_dma.c
@@ -336,7 +336,9 @@
 							    data ?
 							    data->dma_filter :
 							    NULL,
-							    param_array[ch_num]);
+							    param_array ?
+							    param_array[ch_num] :
+							    NULL);
 
 			if (!ux500_channel->dma_chan) {
 				ERR("Dma pipe allocation error dir=%d ch=%d\n",