udp: using datalen to cap ipv6 udp max gso segments

stable inclusion
from stable-v5.10.90
commit abe74fb43378ce4f2d41b9fbe58cbabe5d12b204
bugzilla: 186168 https://gitee.com/openeuler/kernel/issues/I4SHY1

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=abe74fb43378ce4f2d41b9fbe58cbabe5d12b204



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[ Upstream commit 736ef37f ]

The max number of UDP gso segments is intended to cap to
UDP_MAX_SEGMENTS, this is checked in udp_send_skb().

skb->len contains network and transport header len here, we should use
only data len instead.

This is the ipv6 counterpart to the below referenced commit,
which missed the ipv6 change

Fixes: 158390e4 ("udp: using datalen to cap max gso segments")
Signed-off-by: Coco Li <lixiaoyan@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20211223222441.2975883-1-lixiaoyan@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>