net: mediatek: sgmii: fix duplex configuration

The logic of the duplex bit is inverted.  Setting it means half
duplex, not full duplex.

Fix and rename macro to avoid confusion.

Fixes: 7e538372 ("net: ethernet: mediatek: Re-add support SGMII")
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Daniel Golle <daniel@makrotopia.org>
Tested-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mediatek/mtk_eth_soc.h

@@ -519,7 +519,7 @@
 #define SGMII_SPEED_10			FIELD_PREP(SGMII_SPEED_MASK, 0)
 #define SGMII_SPEED_100			FIELD_PREP(SGMII_SPEED_MASK, 1)
 #define SGMII_SPEED_1000		FIELD_PREP(SGMII_SPEED_MASK, 2)
-#define SGMII_DUPLEX_FULL		BIT(4)
+#define SGMII_DUPLEX_HALF		BIT(4)
 #define SGMII_IF_MODE_BIT5		BIT(5)
 #define SGMII_REMOTE_FAULT_DIS		BIT(8)
 #define SGMII_CODE_SYNC_SET_VAL		BIT(9)

drivers/net/ethernet/mediatek/mtk_sgmii.c

@@ -154,11 +154,11 @@ static void mtk_pcs_link_up(struct phylink_pcs *pcs, unsigned int mode,
 		else
 			sgm_mode = SGMII_SPEED_1000;
 
-		if (duplex == DUPLEX_FULL)
-			sgm_mode |= SGMII_DUPLEX_FULL;
+		if (duplex != DUPLEX_FULL)
+			sgm_mode |= SGMII_DUPLEX_HALF;
 
 		regmap_update_bits(mpcs->regmap, SGMSYS_SGMII_MODE,
-				   SGMII_DUPLEX_FULL | SGMII_SPEED_MASK,
+				   SGMII_DUPLEX_HALF | SGMII_SPEED_MASK,
 				   sgm_mode);
 	}
 }