ARM: shmobile: kzm9g-reference: Use falling edge IRQ for LAN9221

The device is configured to generate an active-low interrupt signal that
is automatically deasserted without requiring any action from the host.
Configure the IRQ to trigger on falling edge.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/sh73a0-kzm9g-reference.dts

@@ -83,7 +83,7 @@ lan9220@10000000 {
 		reg = <0x10000000 0x100>;
 		phy-mode = "mii";
 		interrupt-parent = <&irqpin0>;
-		interrupts = <3 IRQ_TYPE_NONE>;	/* active low */
+		interrupts = <3 IRQ_TYPE_EDGE_FALLING>;
 		reg-io-width = <4>;
 		smsc,irq-push-pull;
 		smsc,save-mac-address;