arm64: dts: st: fix timer used for ticks

Remove always-on on generic ARM timer as the clock source provided by
STGEN is deactivated in low power mode, STOP1 by example.

Fixes: 5d30d03 ("arm64: dts: st: introduce stm32mp25 SoCs family")
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20250515151238.1.I85271ddb811a7cf73532fec90de7281cb24ce260@changeid
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

Author: patrickdelaunay

arch/arm64/boot/dts/st/stm32mp251.dtsi

@@ -150,7 +150,7 @@
 			     <GIC_PPI 14 (GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_LOW)>,
 			     <GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_LOW)>,
 			     <GIC_PPI 10 (GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_LOW)>;
-		always-on;
+		arm,no-tick-in-suspend;
 	};
 
 	soc@0 {