MAINTAINERS: add Geliang as reviewer for MPTCP

mainline inclusion
from mainline-v6.7
commit 118ba479d02c5a55e1c1d3c7a43de8937680e67d
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9VYQ9
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=118ba479d02c5a55e1c1d3c7a43de8937680e67d



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For a long time now, Geliang has contributed to a lot of code and
reviews related to MPTCP. So let's reflect that in the MAINTAINERS file.

This should also encourage patch submitters to add him to the CC list.

Acked-by: Geliang Tang <geliang.tang@linux.dev>
Acked-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20231226-upstream-net-20231226-mptcp-prevent-warn-v1-1-1404dcc431ea@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>