tg3: Report the correct number of RSS queues through tg3_get_rxnfc

This patch remove the wrong substraction from info->data in
tg3_get_rxnfc function. Without this patch, the number of RSS
queues reported is less by one.

Reported-by: Michal Soltys <soltys@ziu.info>
Signed-off-by: Siva Reddy Kallam <siva.kallam@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>