net: axienet: fix error return code

Return a negative error code on failure.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
identifier ret; expression e1,e2;
@@
(
if (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret = 0
)
... when != ret = e1
    when != &ret
*if(...)
{
  ... when != ret = e2
      when forall
 return ret;
}
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -1501,6 +1501,7 @@ static int axienet_of_probe(struct platform_device *op)
 	lp->regs = of_iomap(op->dev.of_node, 0);
 	if (!lp->regs) {
 		dev_err(&op->dev, "could not map Axi Ethernet regs.\n");
+		ret = -ENOMEM;
 		goto nodev;
 	}
 	/* Setup checksum offload, but default to off if not specified */
@@ -1563,6 +1564,7 @@ static int axienet_of_probe(struct platform_device *op)
 	np = of_parse_phandle(op->dev.of_node, "axistream-connected", 0);
 	if (!np) {
 		dev_err(&op->dev, "could not find DMA node\n");
+		ret = -ENODEV;
 		goto err_iounmap;
 	}
 	lp->dma_regs = of_iomap(np, 0);