hv_netvsc: remove redundant assignment in netvsc_recv_callback()

hv_netvsc: remove redundant assignment in netvsc_recv_callback()

BugLink: http://bugs.launchpad.net/bugs/1616677
net_device_ctx is assigned in the very beginning of the function and 'net'
pointer doesn't change.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 4baa994dc93287321c1b712d98cb6f721652891b)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>