i2c: s3c24x0: fix the compiler error for exynos4

If CONFIG_SYS_I2C_S3C24X0_SLAVE isn't defined, then complie error should
be occurred.
This patch is for preventing it.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
1 file changed