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/netspace_lite_v2_defconfig b/configs/netspace_lite_v2_defconfig
index 7a4f159..fd690f3 100644
--- a/configs/netspace_lite_v2_defconfig
+++ b/configs/netspace_lite_v2_defconfig
@@ -46,6 +46,7 @@
 CONFIG_SATA_MV=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_MVTWSI=y
+CONFIG_SYS_I2C_SLAVE=0x0
 CONFIG_SYS_I2C_EEPROM_ADDR=0x50
 # CONFIG_MMC is not set
 CONFIG_DM_SPI_FLASH=y