gdsys_rxaui_ctrl: Return old state

Make the gdsys_rxaui_ctrl polarity setting function return the old
state to comply with the API requirements.
Signed-off-by: NMario Six <mario.six@gdsys.cc>

drivers/misc/gdsys_rxaui_ctrl.c

@@ -29,6 +29,7 @@ struct gdsys_rxaui_ctrl_regs {
 
 struct gdsys_rxaui_ctrl_priv {
 	struct regmap *map;
+	bool state;
 };
 
 int gdsys_rxaui_set_polarity_inversion(struct udevice *dev, bool val)
@@ -36,6 +37,8 @@ int gdsys_rxaui_set_polarity_inversion(struct udevice *dev, bool val)
 	struct gdsys_rxaui_ctrl_priv *priv = dev_get_priv(dev);
 	u16 state;
 
+	priv->state = !priv->state;
+
 	rxaui_ctrl_get(priv->map, ctrl_1, &state);
 
 	if (val)
@@ -45,7 +48,7 @@ int gdsys_rxaui_set_polarity_inversion(struct udevice *dev, bool val)
 
 	rxaui_ctrl_set(priv->map, ctrl_1, state);
 
-	return 0;
+	return !priv->state;
 }
 
 static const struct misc_ops gdsys_rxaui_ctrl_ops = {
@@ -58,6 +61,8 @@ int gdsys_rxaui_ctrl_probe(struct udevice *dev)
 
 	regmap_init_mem(dev, &priv->map);
 
+	priv->state = false;
+
 	return 0;
 }