imx8: support parsing i.MX8 Container file

Add parsing i.MX8 Container file support, this is to let
SPL could load images in a container file to destination address.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx8/Kconfig b/arch/arm/mach-imx/imx8/Kconfig
index bbe323d..e9496cb 100644
--- a/arch/arm/mach-imx/imx8/Kconfig
+++ b/arch/arm/mach-imx/imx8/Kconfig
@@ -23,6 +23,12 @@
 config SYS_SOC
 	default "imx8"
 
+config SPL_LOAD_IMX_CONTAINER
+	bool "Enable SPL loading U-Boot as a i.MX Container image"
+	depends on SPL
+	help
+	  This is to let SPL could load i.MX8 Container image
+
 choice
 	prompt "i.MX8 board select"
 	optional