Convert CONFIG_SYS_I2C_MXC et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_MXC
   CONFIG_SYS_I2C_MXC_I2C1
   CONFIG_SYS_I2C_MXC_I2C2
   CONFIG_SYS_I2C_MXC_I2C3
   CONFIG_SYS_I2C_MXC_I2C4

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/udoo_neo_defconfig b/configs/udoo_neo_defconfig
index c83a6dd..13c3198 100644
--- a/configs/udoo_neo_defconfig
+++ b/configs/udoo_neo_defconfig
@@ -9,6 +9,7 @@
 CONFIG_ENV_OFFSET=0x80000
 CONFIG_MX6SX=y
 CONFIG_TARGET_UDOO_NEO=y
+CONFIG_SYS_I2C_MXC_I2C1=y
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="imx6sx-udoo-neo-basic"
 CONFIG_SPL_TEXT_BASE=0x00908000
@@ -38,6 +39,7 @@
 CONFIG_BOUNCE_BUFFER=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
+CONFIG_SYS_I2C_MXC=y
 CONFIG_FSL_USDHC=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y