arm64: smp: Increase secondary CPU boot timeout value

When many debug options are enabled simultaneously (e.g. PROVE_LOCKING,
KMEMLEAK, DEBUG_PAGE_ALLOC, KASAN etc), it is possible for us to timeout
when attempting to boot a secondary CPU and give up. Unfortunately, the
CPU will /eventually/ appear, and sit in the background happily stuck
in a recursive exception due to a NULL stack pointer.

Increase the timeout to 5s, which will of course be enough for anybody.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/smp.c

@@ -123,7 +123,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 		 * time out.
 		 */
 		wait_for_completion_timeout(&cpu_running,
-					    msecs_to_jiffies(1000));
+					    msecs_to_jiffies(5000));
 
 		if (!cpu_online(cpu)) {
 			pr_crit("CPU%u: failed to come online\n", cpu);