dt-bindings: phy: brcm,ns-usb2-phy: bind just a PHY block

The old binding was covering the whole DMU block space (DMU block
contains CRU block which contains USB PHY). It was a bad design,
overkill and a non-generic solution.

Northstar's USB 2.0 PHY is a small block (part of the CRU MFD) and
binding should be designed to represent that properly. Rework the
binding to map just PHY with the "reg" property and use syscon to
reference shared register that controls block access.

The old binding is deprecated now.

Signed-off-by: Rafał Miłecki <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/phy/bcm-ns-usb2-phy.yaml

···
     const: brcm,ns-usb2-phy
 
   reg:
-    items:
-      - description: iomem address range of DMU (Device Management Unit)
+    anyOf:
+      - maxItems: 1
+        description: PHY control register
+      - maxItems: 1
+        description: iomem address range of DMU (Device Management Unit)
+        deprecated: true
 
   reg-names:
     items:
       - const: dmu
+
+  brcm,syscon-clkset:
+    description: phandle to syscon for clkset register
+    $ref: /schemas/types.yaml#/definitions/phandle
 
   clocks:
     items:
···
 required:
   - compatible
   - reg
-  - reg-names
   - clocks
   - clock-names
   - "#phy-cells"
+
+oneOf:
+  - required:
+      - brcm,syscon-clkset
+  - required:
+      - reg-names
 
 additionalProperties: false
 
 examples:
   - |
     #include <dt-bindings/clock/bcm-nsp.h>
-    phy@1800c000 {
+    phy@1800c164 {
         compatible = "brcm,ns-usb2-phy";
-        reg = <0x1800c000 0x1000>;
-        reg-names = "dmu";
+        reg = <0x1800c164 0x4>;
+        brcm,syscon-clkset = <&clkset>;
         clocks = <&genpll BCM_NSP_GENPLL_USB_PHY_REF_CLK>;
         clock-names = "phy-ref-clk";
         #phy-cells = <0>;