dts: arm: delete systick node from SoCs not having the SysTick timer

ARM SysTick peripheral is optional in Cortex-M0 MCUs,
so we delete the respective dts node when the peripheral
is not present.

Signed-off-by: Ioannis Glaropoulos <[email protected]>

Author: ioannisg

dts/arm/nordic/nrf51822.dtsi

@@ -219,6 +219,9 @@
 	arm,num-irq-priority-bits = <2>;
 };
 
+/delete-node/ &systick;
+
+
 &sw_pwm {
 	timer-instance = <1>;
 	channel-count = <3>;