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/mx7dsabresd_qspi_defconfig b/configs/mx7dsabresd_qspi_defconfig
index f5d2f25..3503ddf 100644
--- a/configs/mx7dsabresd_qspi_defconfig
+++ b/configs/mx7dsabresd_qspi_defconfig
@@ -44,6 +44,7 @@
 CONFIG_DFU_RAM=y
 CONFIG_DM_74X164=y
 CONFIG_DM_I2C=y
+CONFIG_SYS_I2C_MXC=y
 CONFIG_SUPPORT_EMMC_BOOT=y
 CONFIG_MMC_IO_VOLTAGE=y
 CONFIG_MMC_UHS_SUPPORT=y