[ Upstream commit 17d91256898402daf4425cc541ac9cbf64574d9a ]

Changing mtu, channels, or buffer sizes ops call to netvsc_attach(),
rndis_set_subchannel(), which always reset the hash key to default
value. That will override hash key changed previously. This patch
fixes the problem by save the hash key, then restore it when we re-
add the netvsc device.

Fixes: ff4a4419 ("netvsc: allow get/set of RSS indirection table")
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: NMichael Kelley <mikelley@microsoft.com>
[sl: fix up subject line]
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>