ARM: dts: imxrt1020-evk: set gpt1 as tick-timer for u-boot

Let's set gpt1 as u-boot timer.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
diff --git a/arch/arm/dts/imxrt1020-evk.dts b/arch/arm/dts/imxrt1020-evk.dts
index a471ff3..b527206 100644
--- a/arch/arm/dts/imxrt1020-evk.dts
+++ b/arch/arm/dts/imxrt1020-evk.dts
@@ -16,6 +16,7 @@
 	chosen {
 		bootargs = "root=/dev/ram";
 		stdout-path = "serial0:115200n8";
+		tick-timer = &gpt1;
 	};
 
 	memory {