Revert "net: macb: Fixed reading MII_LPA register"

This reverts commit 1b0c9914cc75d1570359181ebd493cd5746cb0ed.

Commit 1b0c9914cc75 ("net: macb: Fixed reading MII_LPA register")
causes 100Mbps does not work any more with SiFive FU540 GEM on the
HiFive Unleashed board. Revert it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/net/macb.c b/drivers/net/macb.c
index c99cf66..25f7913 100644
--- a/drivers/net/macb.c
+++ b/drivers/net/macb.c
@@ -643,7 +643,7 @@
 
 	/* First check for GMAC and that it is GiB capable */
 	if (gem_is_gigabit_capable(macb)) {
-		lpa = macb_mdio_read(macb, MII_LPA);
+		lpa = macb_mdio_read(macb, MII_STAT1000);
 
 		if (lpa & (LPA_1000FULL | LPA_1000HALF | LPA_1000XFULL |
 					LPA_1000XHALF)) {