ARM: dts: exynos: Add high speed I2C ports for Exynos5260

Most of the work to support the high speed I2C ports on the Exynos5260
was added in commit 218e1496 ("i2c: exynos5: add support for HSI2C
on Exynos5260 SoC") and the pinctrl nodes have always been available.
All that is missing to get them working is the addition of the DT bindings.

Signed-off-by: Stuart Menefy <stuart.menefy@mathembedded.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>