phy: rockchip-emmc: should be a child device of the GRF

The emmc-phy is fully enclosed in the general register files (GRF).
Therefore as seen from the device-tree it shouldn't be a separate platform-
device but instead a sub-device of the GRF - using the simply-mfd mechanism.

The driver entered the kernel in the current merge-window, so we can still
adapt the binding without needing a fallback, as the binding hasn't been
released with a full kernel yet.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt

@@ -3,17 +3,21 @@ Rockchip EMMC PHY
 
 Required properties:
  - compatible: rockchip,rk3399-emmc-phy
- - rockchip,grf : phandle to the syscon managing the "general
-   register files"
  - #phy-cells: must be 0
  - reg: PHY configure reg address offset in "general
    register files"
 
 Example:
 
-emmcphy: phy {
-	compatible = "rockchip,rk3399-emmc-phy";
-	rockchip,grf = <&grf>;
-	reg = <0xf780>;
-	#phy-cells = <0>;
+
+grf: syscon@ff770000 {
+	compatible = "rockchip,rk3399-grf", "syscon", "simple-mfd";
+
+...
+
+	emmcphy: phy@f780 {
+		compatible = "rockchip,rk3399-emmc-phy";
+		reg = <0xf780>;
+		#phy-cells = <0>;
+	};
 };

drivers/phy/phy-rockchip-emmc.c

@@ -176,7 +176,10 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 	struct regmap *grf;
 	unsigned int reg_offset;
 
-	grf = syscon_regmap_lookup_by_phandle(dev->of_node, "rockchip,grf");
+	if (!dev->parent || !dev->parent->of_node)
+		return -ENODEV;
+
+	grf = syscon_node_to_regmap(dev->parent->of_node);
 	if (IS_ERR(grf)) {
 		dev_err(dev, "Missing rockchip,grf property\n");
 		return PTR_ERR(grf);