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/Bananapi_defconfig b/configs/Bananapi_defconfig
index 41d356b..074f747 100644
--- a/configs/Bananapi_defconfig
+++ b/configs/Bananapi_defconfig
@@ -12,6 +12,7 @@
 CONFIG_SPL_I2C=y
 CONFIG_NETCONSOLE=y
 CONFIG_SCSI_AHCI=y
+CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_PHY_REALTEK=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_RGMII=y