uio: Constify struct kobj_type

uio: Constify struct kobj_type

These 'struct kobj_type' are not modified. They are only used in
kobject_init() which takes a 'const struct kobj_type *ktype'
parameter.

Constifying these structure and moving them to a read-only
section (from data to text), and can increase over all security.

```
[Before]
   text   data    bss    dec    hex    filename
  10330   1908     20  12258   2fe2    drivers/uio/uio.o

[After]
  text    data    bss    dec    hex    filename
  10458   1844     20  12322   3022    drivers/uio/uio.o
```

Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://lore.kernel.org/r/20240904012200.2010916-1-lihongbo22@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>