dt-bindings: display: st7789v: add Inanbo T28CP45TN89

Add compatible value for Inanbo t28cp45tn89 and make reset GPIO non
mandatory, since it might not be connected to the CPU.

Reviewed-by: Michael Riesch <michael.riesch@wolfvision.net>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230714013756.1546769-3-sre@kernel.org