x86/apic: Mark acpi_mp_wake_* variables as __ro_after_init

acpi_mp_wake_mailbox_paddr and acpi_mp_wake_mailbox are initialized once during
ACPI MADT init and never changed.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kai Huang <kai.huang@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Tao Liu <ltao@redhat.com>
Link: https://lore.kernel.org/r/20240614095904.1345461-3-kirill.shutemov@linux.intel.com

arch/x86/kernel/acpi/madt_wakeup.c

@@ -6,10 +6,10 @@
 #include <asm/processor.h>
 
 /* Physical address of the Multiprocessor Wakeup Structure mailbox */
-static u64 acpi_mp_wake_mailbox_paddr;
+static u64 acpi_mp_wake_mailbox_paddr __ro_after_init;
 
 /* Virtual address of the Multiprocessor Wakeup Structure mailbox */
-static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox;
+static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox __ro_after_init;
 
 static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip)
 {