clocksource/drivers/arm_arch_timer: Remove unnecessary ‘0’ values from irq

The irq variable is initialized whatever the code path, it is poinless
to initialize when declaring it.
Signed-off-by: Li kunyu <kunyu@nfschina.com>
Link: https://lore.kernel.org/r/20240705040729.21961-1-kunyu@nfschina.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/arm_arch_timer.c

@@ -1556,7 +1556,7 @@ static int __init
 arch_timer_mem_frame_register(struct arch_timer_mem_frame *frame)
 {
 	void __iomem *base;
-	int ret, irq = 0;
+	int ret, irq;
 
 	if (arch_timer_mem_use_virtual)
 		irq = frame->virt_irq;