net: move definition of pcpu_lstats to header file

[ Upstream commit 52bb6677d530d37055092d86b4eab69dce6c166a ]

pcpu_lstats is defined in several files, so unify them as one
and move to header file

Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 1ca1ba465e55 ("geneve: make sure to pull inner header in geneve_rx()")
Signed-off-by: Sasha Levin <sashal@kernel.org>