macvlan: Fix rx counters update in macvlan_handle_frame()

Fix macvlan_handle_frame() to update the rx counters based
on the return value of the vlan->receive call.

Updated the patch to not do any packet count drops when the interface
is down based on Herber'ts comments.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>