powerpc/smp: Add __ro_after_init attribute

There are some variables that are only updated at boot time.
So add __ro_after_init attribute to such variables
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214180720.310852-4-srikar@linux.vnet.ibm.com

arch/powerpc/kernel/smp.c

@@ -77,10 +77,10 @@ static DEFINE_PER_CPU(int, cpu_state) = { 0 };
 #endif
 
 struct task_struct *secondary_current;
-bool has_big_cores;
-bool coregroup_enabled;
-bool thread_group_shares_l2;
-bool thread_group_shares_l3;
+bool has_big_cores __ro_after_init;
+bool coregroup_enabled __ro_after_init;
+bool thread_group_shares_l2 __ro_after_init;
+bool thread_group_shares_l3 __ro_after_init;
 
 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
 DEFINE_PER_CPU(cpumask_var_t, cpu_smallcore_map);
@@ -987,7 +987,7 @@ static int __init init_thread_group_cache_map(int cpu, int cache_property)
 	return 0;
 }
 
-static bool shared_caches;
+static bool shared_caches __ro_after_init;
 
 #ifdef CONFIG_SCHED_SMT
 /* cpumask of CPUs with asymmetric SMT dependency */