drivers/net/s2io.c: fix sparse warning: symbol shadows an earlier one

Impact: Remove redundant inner scope variable.

Fix this sparse warning:
  drivers/net/s2io.c:7223:21: warning: symbol 'i' shadows an earlier one
  drivers/net/s2io.c:7184:13: originally declared here
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/s2io.c

@@ -7220,7 +7220,6 @@ static int s2io_card_up(struct s2io_nic * sp)
 
 	/* Initialise napi */
 	if (config->napi) {
-		int i;
 		if (config->intr_type ==  MSI_X) {
 			for (i = 0; i < sp->config.rx_ring_num; i++)
 				napi_enable(&sp->mac_control.rings[i].napi);