powerpc/64: Convert patch_instruction() to patch_u32()

This use of patch_instruction() is working on 32 bit data, and can fail
if the data looks like a prefixed instruction and the extra write
crosses a page boundary. Use patch_u32() to fix the write size.

Fixes: 8734b41b ("powerpc/module_64: Fix livepatching for RO modules")
Link: https://lore.kernel.org/all/20230203004649.1f59dbd4@yea/


Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Tested-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240515024445.236364-4-bgray@linux.ibm.com