i2c:gpio:s5p: Enable I2C GPIO on the GONI target

This patch enables the software I2C for GONI reference target.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
Cc: Heiko Schocher <hs@denx.de>