dt-bindings: usb: sunxi-musb: add Allwinner A523 compatible string

The Allwinner A523/T527 SoCs have a MUSB controller fully compatible to
the D1 (and ultimately the A33), with five endpoints.

Add the new name to the list of compatible strings.

Signed-off-by: Andre Przywara <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/usb/allwinner,sun4i-a10-musb.yaml

···
               - allwinner,sun8i-a83t-musb
               - allwinner,sun20i-d1-musb
               - allwinner,sun50i-h6-musb
+              - allwinner,sun55i-a523-musb
           - const: allwinner,sun8i-a33-musb
       - items:
           - const: allwinner,sun50i-h616-musb