net: macb: make magic-packet property generic

As requested by Rob Herring on patch
https://patchwork.ozlabs.org/patch/580862/.

This is a new property that it's still in net-next and has never been
used in production, so we are not breaking anything with the
incompatible binding change.
Signed-off-by: Sergio Prado <sergio.prado@e-labworks.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/macb.txt

@@ -25,7 +25,7 @@ Required properties:
 
 Optional properties for PHY child node:
 - reset-gpios : Should specify the gpio for phy reset
-- cdns,magic-packet : If present, indicates that the hardware supports waking
+- magic-packet : If present, indicates that the hardware supports waking
   up via magic packet.
 
 Examples:

drivers/net/ethernet/cadence/macb.c

@@ -2929,7 +2929,7 @@ static int macb_probe(struct platform_device *pdev)
 		bp->jumbo_max_len = macb_config->jumbo_max_len;
 
 	bp->wol = 0;
-	if (of_get_property(np, "cdns,magic-packet", NULL))
+	if (of_get_property(np, "magic-packet", NULL))
 		bp->wol |= MACB_WOL_HAS_MAGIC_PACKET;
 	device_init_wakeup(&pdev->dev, bp->wol & MACB_WOL_HAS_MAGIC_PACKET);