MAINTAINERS: Add myself as reviewer of ARM64 BPF JIT

I am working on ARM64 BPF JIT for a while, hence add myself
as reviewer.
Signed-off-by: Xu Kuohai <xukuohai@huaweicloud.com>
Acked-by: Hengqi Chen <hengqi.chen@gmail.com>
Link: https://lore.kernel.org/r/20240516020928.156125-1-xukuohai@huaweicloud.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

MAINTAINERS

@@ -3816,6 +3816,7 @@ BPF JIT for ARM64
 M:	Daniel Borkmann <daniel@iogearbox.net>
 M:	Alexei Starovoitov <ast@kernel.org>
 M:	Puranjay Mohan <puranjay@kernel.org>
+R:	Xu Kuohai <xukuohai@huaweicloud.com>
 L:	bpf@vger.kernel.org
 S:	Supported
 F:	arch/arm64/net/