UPSTREAM: vxlan: fix error return code in vxlan_fdb_append

[ 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>
(cherry picked from commit 435142fb)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Id0925ddedd1af8a8a7ca0cc79f8d7151565ed7a7