dt-bindings: i2c: dw: merge duplicate compatible entry.

Each vendor have an items entry of its own compatible, It is needless
and some can be merged as it share the same base "snps,designware-i2c"
compatible.

Merge the duplicate compatible entry into one item entry.

Signed-off-by: Inochi Amaoto <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Andi Shyti <[e-mail]>

Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml

···
           - const: renesas,r9a06g032-i2c  # RZ/N1D
           - const: renesas,rzn1-i2c       # RZ/N1
           - const: snps,designware-i2c
-      - description: Microsemi Ocelot SoCs I2C controller
-        items:
-          - const: mscc,ocelot-i2c
-          - const: snps,designware-i2c
       - description: Baikal-T1 SoC System I2C controller
         const: baikal,bt1-sys-i2c
-      - description: T-HEAD TH1520 SoCs I2C controller
-        items:
-          - const: thead,th1520-i2c
+      - items:
+          - enum:
+              - mscc,ocelot-i2c
+              - thead,th1520-i2c
           - const: snps,designware-i2c
 
   reg: