i2c: exynos5: use core helper to get driver data

Driver core provides of_device_get_match_data which can be used
to get driver data instead of custom helper.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>