dt-bindings: gpio: Convert ti,keystone-dsp-gpio to DT schema

Convert the TI Keystone DSP GPIO binding to DT schema format. The
"ti,syscon-dev" property was wrong and should be "gpio,syscon-dev"
instead.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250714202850.3011952-1-robh@kernel.org


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>