i2c: exynos5: add High Speed I2C controller driver

Adds support for High Speed I2C driver found in Exynos5 and
later SoCs from Samsung.

Driver only supports Device Tree method.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Signed-off-by: Taekgyun Ko <taeggyun.ko@samsung.com>
Reviewed-by: Simon Glass <sjg@google.com>
Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
Signed-off-by: Andrew Bresticker <abrestic@google.com>
[wsa: rebased to v3.12-rc4 (no of_i2c.h anymore)]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>