arm64: kprobes: call set_memory_rox() for kprobe page

The kprobe page is allocated by execmem allocator with ROX permission.
It needs to call set_memory_rox() to set proper permission for the
direct map too. It was missed.

Fixes: 10d5e97c ("arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page")
Cc: <stable@vger.kernel.org>
Signed-off-by: Yang Shi <yang@os.amperecomputing.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>