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/ls1046ardb_emmc_defconfig b/configs/ls1046ardb_emmc_defconfig
index 88c060b..43b0c7e 100644
--- a/configs/ls1046ardb_emmc_defconfig
+++ b/configs/ls1046ardb_emmc_defconfig
@@ -6,6 +6,10 @@
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_ENV_SIZE=0x2000
 CONFIG_ENV_OFFSET=0x300000
+CONFIG_SYS_I2C_MXC_I2C1=y
+CONFIG_SYS_I2C_MXC_I2C2=y
+CONFIG_SYS_I2C_MXC_I2C3=y
+CONFIG_SYS_I2C_MXC_I2C4=y
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="fsl-ls1046a-rdb"
 CONFIG_SPL_TEXT_BASE=0x10000000