dt-bindings: gpio: gpio-davinci: Convert to json-schema

Convert gpio-davinci dt-binding documentation from txt to yaml format.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>