x86/mce: Make mce_subsys const

Now that the driver core can properly handle constant struct bus_type,
make mce_subsys a constant structure.

Suggested-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Ricardo B. Marliere <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: rbmarliere

arch/x86/kernel/cpu/mce/core.c

@@ -2431,7 +2431,7 @@ static void mce_enable_ce(void *all)
 		__mcheck_cpu_init_timer();
 }
 
-static struct bus_type mce_subsys = {
+static const struct bus_type mce_subsys = {
 	.name		= "machinecheck",
 	.dev_name	= "machinecheck",
 };