Convert CONFIG_SYS_I2C_MVTWSI to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_MVTWSI

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/km_kirkwood_128m16_defconfig b/configs/km_kirkwood_128m16_defconfig
index b93fcbf..1f97c9e 100644
--- a/configs/km_kirkwood_128m16_defconfig
+++ b/configs/km_kirkwood_128m16_defconfig
@@ -48,6 +48,7 @@
 CONFIG_BOOTCOUNT_RAM=y
 CONFIG_SYS_I2C_SOFT=y
 CONFIG_SYS_I2C_SOFT_SLAVE=0x0
+CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_SYS_I2C_EEPROM_ADDR=0x50
 # CONFIG_MMC is not set
 CONFIG_MTD=y