Convert CONFIG_MX7D to Kconfig

This converts the following to Kconfig:
   CONFIG_MX7D

Cc: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: NTom Rini <trini@konsulko.com>

arch/arm/mach-imx/mx7/Kconfig

@@ -91,6 +91,7 @@ config TARGET_COLIBRI_IMX7
 	select DM
 	select DM_SERIAL
 	select DM_THERMAL
+	select MX7D
 	imply CMD_DM
 
 endchoice

configs/colibri_imx7_defconfig

@@ -12,7 +12,7 @@ CONFIG_IMX_RDC=y
 CONFIG_IMX_BOOTAUX=y
 CONFIG_IMX_HAB=y
 CONFIG_DISTRO_DEFAULTS=y
-CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/toradex/colibri_imx7/imximage.cfg,MX7D"
+CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/toradex/colibri_imx7/imximage.cfg"
 CONFIG_BOOTDELAY=1
 # CONFIG_USE_BOOTCOMMAND is not set
 CONFIG_USE_PREBOOT=y

configs/colibri_imx7_emmc_defconfig

@@ -14,7 +14,7 @@ CONFIG_IMX_BOOTAUX=y
 CONFIG_IMX_HAB=y
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y
-CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/toradex/colibri_imx7/imximage.cfg,MX7D"
+CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/toradex/colibri_imx7/imximage.cfg"
 CONFIG_BOOTDELAY=1
 # CONFIG_USE_BOOTCOMMAND is not set
 CONFIG_USE_PREBOOT=y