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/A20-Olimex-SOM204-EVB_defconfig b/configs/A20-Olimex-SOM204-EVB_defconfig
index e2388b7..af3eb5b 100644
--- a/configs/A20-Olimex-SOM204-EVB_defconfig
+++ b/configs/A20-Olimex-SOM204-EVB_defconfig
@@ -15,6 +15,7 @@
 CONFIG_SPL_I2C=y
 CONFIG_SCSI_AHCI=y
 CONFIG_FASTBOOT_CMD_OEM_FORMAT=y
+CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_PHY_ADDR=3
 CONFIG_PHY_MICREL=y
 CONFIG_PHY_MICREL_KSZ90X1=y