vxlan: move to its own directory

stable inclusion
from stable-v5.10.190
commit d2741769d512ea1bf5544bf85da7602e64f82e45
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I928UI

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d2741769d512ea1bf5544bf85da7602e64f82e45



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[ Upstream commit 67653936 ]

vxlan.c has grown too long. This patch moves
it to its own directory. subsequent patches add new
functionality in new files.

Signed-off-by: Roopa Prabhu <roopa@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 94d166c5 ("vxlan: calculate correct header length for GPE")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>