ARM: dts: am437x-gp-evm: Correct tps65218 irq type

According to the documentation the interrupt line is active low.

The patch will silence the warning from gic_irq_domain_translate():
"Make it clear that broken DTs are... broken"
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am437x-gp-evm.dts

@@ -543,7 +543,7 @@ &i2c0 {
 	tps65218: tps65218@24 {
 		reg = <0x24>;
 		compatible = "ti,tps65218";
-		interrupts = <GIC_SPI 7 IRQ_TYPE_NONE>; /* NMIn */
+		interrupts = <GIC_SPI 7 IRQ_TYPE_LEVEL_LOW>; /* NMIn */
 		interrupt-controller;
 		#interrupt-cells = <2>;