dt-bindings/display: ingenic: Add compatible string for the JZ4760(B)

Add compatible strings for the LCD controllers found in the JZ4760 and
JZ4760B SoCs from Ingenic.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc: devicetree@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20220708205406.96473-2-paul@crapouillou.net