psample: Add a fwd declaration for skbuff

stable inclusion
from stable-5.10.60
commit 30b1fc47f7657da952a20c16892e8d21190eefbf
bugzilla: 177018 https://gitee.com/openeuler/kernel/issues/I4EAUG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=30b1fc47f7657da952a20c16892e8d21190eefbf



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[ Upstream commit beb7f2de ]

Without this there is a warning if source files include psample.h
before skbuff.h or doesn't include it at all.

Fixes: 6ae0a628 ("net: Introduce psample, a new genetlink channel for packet sampling")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Link: https://lore.kernel.org/r/20210808065242.1522535-1-roid@nvidia.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>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>