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/db-mv784mp-gp_defconfig b/configs/db-mv784mp-gp_defconfig
index a4345ba..2442832 100644
--- a/configs/db-mv784mp-gp_defconfig
+++ b/configs/db-mv784mp-gp_defconfig
@@ -49,6 +49,7 @@
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_SPL_OF_TRANSLATE=y
 CONFIG_SATA_MV=y
+CONFIG_SYS_I2C_MVTWSI=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y