Revert "parisc: Only list existing CPUs in cpu_possible_mask"

This reverts commit 0921244.

It broke CPU hotplugging because it modifies the __cpu_possible_mask
after bootup, so that it will be different than nr_cpu_ids, which
then effictively breaks the workqueue setup code and triggers crashes
when shutting down CPUs at runtime.

Guenter was the first who noticed the wrong values in __cpu_possible_mask,
since the cpumask Kunit tests were failig.

Reverting this commit fixes both issues, but sadly brings back this
uncritical runtime warning:
register_cpu_capacity_sysctl: too early to get CPU4 device!

Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lkml.org/lkml/2024/2/4/146
Link: https://lore.kernel.org/lkml/Zb0mbHlIud_bqftx@slm.duckdns.org/t/
Cc: stable@vger.kernel.org # 6.0+

Author: hdeller

arch/parisc/kernel/processor.c

@@ -172,7 +172,6 @@ static int __init processor_probe(struct parisc_device *dev)
 	p->cpu_num = cpu_info.cpu_num;
 	p->cpu_loc = cpu_info.cpu_loc;
 
-	set_cpu_possible(cpuid, true);
 	store_cpu_topology(cpuid);
 
 #ifdef CONFIG_SMP
@@ -474,13 +473,6 @@ static struct parisc_driver cpu_driver __refdata = {
  */
 void __init processor_init(void)
 {
-	unsigned int cpu;
-
 	reset_cpu_topology();
-
-	/* reset possible mask. We will mark those which are possible. */
-	for_each_possible_cpu(cpu)
-		set_cpu_possible(cpu, false);
-
 	register_parisc_driver(&cpu_driver);
 }