ARM: dts: exynos: Convert to new i2c-gpio bindings

The updated "i2c-gpio" driver bindings require to define the SDA and SCL
GPIO lines in the separate properties and mark both as GPIO_OPEN_DRAIN.
Covert all Exynos dts files to follow this style.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>