Connector: Correctly set the error code in case of success when dispatching receive callbacks

The recent changes to the connector code introduced this bug where even
when a callback was invoked, we would return an error resulting in
double freeing of the skb. This patch fixes this bug.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: stable <stable@kernel.org>  [.39]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>