dt-bindings: ethernet: eswin: fix yaml schema issues

eswin,hsp-sp-csr attribute is one phandle with multiple arguments,
so the syntax should be in the form of:
items:
- items:
- description: ...
- description: ...
- description: ...
- description: ...

To align with the description of the 'eswin-sp-csr'
attribute in the mmc,usb modules, the description
of the 'eswin,hsp-sp-csr' attribute has been modified.

Fixes: 888bd0eca93c ("dt-bindings: ethernet: eswin: Document for EIC7700 SoC")
Reported-by: Rob Herring (Arm) <[e-mail]>
Closes: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Shangjuan Wei <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/devicetree/bindings/net/eswin,eic7700-eth.yaml

···
     enum: [0, 200, 600, 1200, 1600, 1800, 2000, 2200, 2400]
 
   eswin,hsp-sp-csr:
+    description:
+      HSP CSR is to control and get status of different high-speed peripherals
+      (such as Ethernet, USB, SATA, etc.) via register, which can tune
+      board-level's parameters of PHY, etc.
     $ref: /schemas/types.yaml#/definitions/phandle-array
     items:
-      - description: Phandle to HSP(High-Speed Peripheral) device
-      - description: Offset of phy control register for internal
-                     or external clock selection
-      - description: Offset of AXI clock controller Low-Power request
-                     register
-      - description: Offset of register controlling TX/RX clock delay
-    description: |
-      High-Speed Peripheral device needed to configure clock selection,
-      clock low-power mode and clock delay.
+      - items:
+          - description: Phandle to HSP(High-Speed Peripheral) device
+          - description: Offset of phy control register for internal
+                         or external clock selection
+          - description: Offset of AXI clock controller Low-Power request
+                         register
+          - description: Offset of register controlling TX/RX clock delay
 
 required:
   - compatible