arm64: Constify struct kobj_type

'struct kobj_type' is not modified. It is only used in kobject_init()
which takes a 'const struct kobj_type *ktype' parameter.

Constifying this structure moves some data to a read-only section,
so increase over all security.

On a x86_64, compiled with arm defconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   5602	    548	    352	   6502	   1966	arch/arm64/kernel/cpuinfo.o

After:
======
   text    data     bss     dec     hex filename
   5650     500     352    6502    1966 arch/arm64/kernel/cpuinfo.o

Signed-off-by: Huang Xiaojia <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: hsiaoh2

arch/arm64/kernel/cpuinfo.c

@@ -280,7 +280,7 @@ const struct seq_operations cpuinfo_op = {
 };
 
 
-static struct kobj_type cpuregs_kobj_type = {
+static const struct kobj_type cpuregs_kobj_type = {
 	.sysfs_ops = &kobj_sysfs_ops,
 };