MAINTAINERS: Update powerpc BPF JIT maintainers

Hari Bathini has been updating and maintaining the powerpc BPF JIT since
a while now. Christophe Leroy has been doing the same for 32-bit
powerpc. Add them as maintainers for the powerpc BPF JIT.

I am no longer actively looking into the powerpc BPF JIT. Change my role
to that of a reviewer so that I can help with the odd query.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Link: https://lore.kernel.org/bpf/24fea21d9d4458973aadd6a02bb1bf558b8bd0b2.1720944897.git.naveen@kernel.org