i2c: samsung: register i2c busses for Exynso5420 and Exynos5250

This patch adds the U_BOOT_I2C_ADAP_COMPLETE defines for channels
on Exynos5420 and Exynos5250 and also adds support for init function
for hsi2c channels

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>