net: smc91x: take into account register shift

This aligns smc91x with its cousin, namely smc911x.c.
This also allows the driver to run also in a device-tree based lubbock
board build, on which it was tested.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/smsc/smc91x.c

@@ -2323,6 +2323,9 @@ static int smc_drv_probe(struct platform_device *pdev)
 		} else {
 			lp->cfg.flags |= SMC91X_USE_16BIT;
 		}
+		if (!device_property_read_u32(&pdev->dev, "reg-shift",
+					      &val))
+			lp->io_shift = val;
 	}
 #endif