net/vxlan: Go over all candidate streams for GRO matching

The loop in vxlan_gro_receive() over the current set of candidates for
coalescing was wrongly aborted once a match was found. In rare cases,
this can cause a false-positives matching in the next layer GRO checks.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>