pcnet32: Remove pointless memory barriers

These two memory barriers in performance-critical paths are not needed
on x86.  Even if some other architecture does buffer PCI I/O space
writes, the existing memory-mapped I/O barriers are unlikely to be what
is needed.

Signed-off-by: John Dykstra <john.dykstra1@gmail.com>
Acked-by:  Don Fry <pcnet32@verizon.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pcnet32.c

@@ -1405,7 +1405,7 @@ static int pcnet32_poll(struct napi_struct *napi, int budget)
 
 		/* Set interrupt enable. */
 		lp->a.write_csr(ioaddr, CSR0, CSR0_INTEN);
-		mmiowb();
+
 		spin_unlock_irqrestore(&lp->lock, flags);
 	}
 	return work_done;
@@ -2597,7 +2597,7 @@ pcnet32_interrupt(int irq, void *dev_id)
 			val = lp->a.read_csr(ioaddr, CSR3);
 			val |= 0x5f00;
 			lp->a.write_csr(ioaddr, CSR3, val);
-			mmiowb();
+
 			__napi_schedule(&lp->napi);
 			break;
 		}