vxlan: fix error return code in vxlan_fdb_append

stable inclusion
from stable-v5.10.113
commit e129c55153c8aba74e4c73451399f12dacf6347d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ISAH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e129c55153c8aba74e4c73451399f12dacf6347d



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[ Upstream commit 7cea5560 ]

When kmalloc and dst_cache_init failed,
should return ENOMEM rather than ENOBUFS.

Signed-off-by: Hongbin Wang <wh_bin@126.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>