net: fsl: Fix error checking for platform_get_irq()

The gianfar driver has recently been enabled on arm64 but fails to build
since it check the return value of platform_get_irq() against NO_IRQ. Fix
this by instead checking for a negative error code.

Even on ARM where this code was previously being built this check was
incorrect since platform_get_irq() returns a negative error code which
may not be exactly the (unsigned int)(-1) that NO_IRQ is defined to be.
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/gianfar_ptp.c

@@ -467,7 +467,7 @@ static int gianfar_ptp_probe(struct platform_device *dev)
 
 	etsects->irq = platform_get_irq(dev, 0);
 
-	if (etsects->irq == NO_IRQ) {
+	if (etsects->irq < 0) {
 		pr_err("irq not in device tree\n");
 		goto no_node;
 	}