hv_netvsc: fix network namespace issues with VF support

When finding the parent netvsc device, the search needs to be across
all netvsc device instances (independent of network namespace).

Find parent device of VF using upper_dev_get routine which
searches only adjacent list.

Fixes: e8ff40d4 ("hv_netvsc: improve VF device matching")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>

netns aware byref
Signed-off-by: David S. Miller <davem@davemloft.net>