dt-bindings: memory-controllers: ti,gpmc-child: drop redundant part of title

dt-bindings: memory-controllers: ti,gpmc-child: drop redundant part of title

The Devicetree bindings document does not have to say in the title that
it is a "Devicetree binding", but instead just describe the hardware.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # MMC
Link: https://lore.kernel.org/r/20221216163815.522628-3-krzysztof.kozlowski@linaro.org
Signed-off-by: Rob Herring <robh@kernel.org>