net: sched: Use struct_size() helper in kvmalloc()

mainline inclusion
from mainline-v5.16-rc1
commit 12929198
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6SFHJ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=129291980f4901ae68ee3ba4344bdc38cf5f800d

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Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows
that, in the worst scenario, could lead to heap overflows.

Link: https://github.com/KSPP/linux/issues/160


Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20210929201718.GA342296@embeddedor


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>