dt-bindings: display: Fix example in nwl-dsi.yaml

dt-bindings: display: Fix example in nwl-dsi.yaml

The example is now validated against rocktech,jh057n00900 schema
that was ported to yaml, and didn't validate with:

- '#address-cells', '#size-cells', 'port@0' do not match any of
  the regexes: 'pinctrl-[0-9]+'
- 'vcc-supply' is a required property
- 'iovcc-supply' is a required property
- 'reset-gpios' is a required property

Fix it.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Ondrej Jirman <megous@megous.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200703114717.2140832-2-megous@megous.com