gianfar: Fix build with CONFIG_PM=y

commit fba4ed03 ("gianfar: Add Multiple
Queue Support") introduced the following build failure:

  CC      gianfar.o
gianfar.c: In function 'gfar_restore':
gianfar.c:1249: error: request for member 'napi' in something not a structure or union

This patch fixes the issue.
Signed-off-by: NAnton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/gianfar.c

@@ -1246,7 +1246,7 @@ static int gfar_restore(struct device *dev)
 		phy_start(priv->phydev);
 
 	netif_device_attach(ndev);
-	napi_enable(&priv->gfargrp.napi);
+	enable_napi(priv);
 
 	return 0;
 }