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/pico-nymph-imx7d_defconfig b/configs/pico-nymph-imx7d_defconfig
index 41208c6..fb1834e 100644
--- a/configs/pico-nymph-imx7d_defconfig
+++ b/configs/pico-nymph-imx7d_defconfig
@@ -6,6 +6,10 @@
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_ENV_SIZE=0x2000
 CONFIG_ENV_OFFSET=0xC0000
+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="imx7d-pico-pi"
 CONFIG_TARGET_PICO_IMX7D=y
@@ -55,6 +59,7 @@
 CONFIG_FASTBOOT_CMD_OEM_FORMAT=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
+CONFIG_SYS_I2C_MXC=y
 CONFIG_SUPPORT_EMMC_BOOT=y
 CONFIG_FSL_USDHC=y
 CONFIG_MTD=y