regulator: uniphier: Add binding for NX1 SoC

Update USB-VBUS binding document for UniPhier NX1 SoC.
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/1634520605-16583-2-git-send-email-hayashi.kunihiko@socionext.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/socionext,uniphier-regulator.yaml

@@ -27,6 +27,7 @@ properties:
       - socionext,uniphier-pxs2-usb3-regulator
       - socionext,uniphier-ld20-usb3-regulator
       - socionext,uniphier-pxs3-usb3-regulator
+      - socionext,uniphier-nx1-usb3-regulator
 
   reg:
     maxItems: 1