sysctl: add proc_dou8vec_minmax()

stable inclusion
from stable-v5.10.178
commit 389dab6142d742f91010f38de0f1f2f440b97e1b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8D927

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=389dab6142d742f91010f38de0f1f2f440b97e1b



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[ Upstream commit cb944413 ]

Networking has many sysctls that could fit in one u8.

This patch adds proc_dou8vec_minmax() for this purpose.

Note that the .extra1 and .extra2 fields are pointing
to integers, because it makes conversions easier.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: dc5110c2 ("tcp: restrict net.ipv4.tcp_app_win")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>