dm: i2c: s3c24x0: adjust to dm-i2c api

This commit adjusts the s3c24x0 driver to new i2c api
based on driver-model. The driver supports standard
and high-speed i2c as previous.

Tested on Trats2, Odroid U3, Arndale, Odroid XU3

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Tested-by: Simon Glass <sjg@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Heiko Schocher <hs@denx.de>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>