Convert CONFIG_SYS_I2C_SPEED et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_SPEED
   CONFIG_SYS_I2C_SLAVE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/CHIP_pro_defconfig b/configs/CHIP_pro_defconfig
index 12db61b..34f609a 100644
--- a/configs/CHIP_pro_defconfig
+++ b/configs/CHIP_pro_defconfig
@@ -14,6 +14,8 @@
 CONFIG_ENV_UBI_PART="UBI"
 CONFIG_ENV_UBI_VOLUME="uboot-env"
 CONFIG_SYS_I2C_MVTWSI=y
+CONFIG_SYS_I2C_SLAVE=0x7f
+CONFIG_SYS_I2C_SPEED=400000
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y