tg3: Fix Read DMA workaround for 5719 A0.

The workaround was mis-applied to all 5719 and 5720 chips.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/tg3.c

@@ -9086,8 +9086,7 @@ static int tg3_reset_hw(struct tg3 *tp, int reset_phy)
 	    GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_57780 ||
 	    tg3_flag(tp, 57765_PLUS)) {
 		val = tr32(TG3_RDMA_RSRVCTRL_REG);
-		if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5719 ||
-		    GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5720) {
+		if (tp->pci_chip_rev_id == CHIPREV_ID_5719_A0) {
 			val &= ~(TG3_RDMA_RSRVCTRL_TXMRGN_MASK |
 				 TG3_RDMA_RSRVCTRL_FIFO_LWM_MASK |
 				 TG3_RDMA_RSRVCTRL_FIFO_HWM_MASK);