tg3: Prepare for larger rx ring sizes

This patch adds two new variables to track the size of the standard and
jumbo rx producer ring sizes.  The code is then pivoted to these
variables from preprocessor constants.
Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.h

@@ -2762,6 +2762,8 @@ struct tg3 {
 	void				(*write32_rx_mbox) (struct tg3 *, u32,
 							    u32);
 	u32				rx_copy_thresh;
+	u32				rx_std_ring_mask;
+	u32				rx_jmb_ring_mask;
 	u32				rx_pending;
 	u32				rx_jumbo_pending;
 	u32				rx_std_max_post;