net: netcp: support probe deferral

The netcp driver shouldn't proceed until the knav qmss and dma
devices are ready. So return -EPROBE_DEFER if these devices are not
ready.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/netcp_core.c

@@ -2158,6 +2158,10 @@ static int netcp_probe(struct platform_device *pdev)
 	struct netcp_module *module;
 	int ret;
 
+	if (!knav_dma_device_ready() ||
+	    !knav_qmss_device_ready())
+		return -EPROBE_DEFER;
+
 	if (!node) {
 		dev_err(dev, "could not find device info\n");
 		return -ENODEV;