net: add skb_set_end_offset() helper

mainline inclusion
from mainline-v5.18-rc1
commit 763087da
category: bugfix
bugzilla: 186761, https://gitee.com/openeuler/kernel/issues/I60MPY
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=763087dab97547230a6807c865a6a5ae53a59247



--------------------------------

We have multiple places where this helper is convenient,
and plan using it in the following patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lu Wei <luwei32@huawei.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>