MAINTAINERS/bpf: Update Andrii's entry.

Andrii has been a de-facto maintainer for libbpf and other components.
Update maintainers entry to acknowledge his work de-jure.

The folks with git write permissions will continue to follow the rule
of not applying their own patches unless absolutely trivial.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201112180340.45265-1-alexei.starovoitov@gmail.com

Author: Alexei Starovoitov

MAINTAINERS

@@ -3243,10 +3243,10 @@ F:	drivers/iio/accel/bma400*
 BPF (Safe dynamic programs and tools)
 M:	Alexei Starovoitov <ast@kernel.org>
 M:	Daniel Borkmann <daniel@iogearbox.net>
+M:	Andrii Nakryiko <andrii@kernel.org>
 R:	Martin KaFai Lau <kafai@fb.com>
 R:	Song Liu <songliubraving@fb.com>
 R:	Yonghong Song <yhs@fb.com>
-R:	Andrii Nakryiko <andrii@kernel.org>
 R:	John Fastabend <john.fastabend@gmail.com>
 R:	KP Singh <kpsingh@chromium.org>
 L:	netdev@vger.kernel.org