Kuser code should be inside .rodata.

Now code in kuser32.S is inside .text section and never executed.
Move it to .rodata.
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Link: https://lore.kernel.org/r/20220531015350.233827-1-chenzhongjin@huawei.comSigned-off-by: Will Deacon <will@kernel.org>