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/marsboard_defconfig b/configs/marsboard_defconfig
index a9cff22..2c7906c 100644
--- a/configs/marsboard_defconfig
+++ b/configs/marsboard_defconfig
@@ -7,6 +7,9 @@
 CONFIG_ENV_SECT_SIZE=0x2000
 CONFIG_MX6Q=y
 CONFIG_TARGET_EMBESTMX6BOARDS=y
+CONFIG_SYS_I2C_MXC_I2C1=y
+CONFIG_SYS_I2C_MXC_I2C2=y
+CONFIG_SYS_I2C_MXC_I2C3=y
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="imx6q-marsboard"
 CONFIG_DISTRO_DEFAULTS=y
@@ -31,6 +34,7 @@
 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_DM_SPI_FLASH=y
 CONFIG_SF_DEFAULT_MODE=0