imx: build flash.bin for i.MX8

Build flash.bin for i.MX8 when SPL enabled.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index 30117f3..9c7ce9e 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -106,6 +106,7 @@
 ifeq ($(CONFIG_ARCH_IMX8), y)
 CNTR_DEPFILES := $(srctree)/tools/imx_cntr_image.sh
 IMAGE_TYPE := imx8image
+SPL_DEPFILE_EXISTS := $(shell $(CPP) $(cpp_flags) -x c -o spl/u-boot-spl.cfgout $(srctree)/$(IMX_CONFIG); if [ -f spl/u-boot-spl.cfgout ]; then $(CNTR_DEPFILES) spl/u-boot-spl.cfgout; echo $$?; fi)
 DEPFILE_EXISTS := $(shell $(CPP) $(cpp_flags) -x c -o u-boot-dtb.cfgout $(srctree)/$(IMX_CONFIG); if [ -f u-boot-dtb.cfgout ]; then $(CNTR_DEPFILES) u-boot-dtb.cfgout; echo $$?; fi)
 else ifeq ($(CONFIG_ARCH_IMX8M), y)
 IMAGE_TYPE := imx8mimage
@@ -154,6 +155,18 @@
 endif
 endif
 
+ifeq ($(CONFIG_ARCH_IMX8), y)
+SPL:
+
+MKIMAGEFLAGS_flash.bin = -n spl/u-boot-spl.cfgout -T $(IMAGE_TYPE) -e 0x100000
+flash.bin: MKIMAGEOUTPUT = flash.log
+
+flash.bin: spl/u-boot-spl.bin u-boot.itb FORCE
+ifeq ($(SPL_DEPFILE_EXISTS),0)
+	$(call if_changed,mkimage)
+endif
+endif
+
 else
 MKIMAGEFLAGS_SPL = -n $(filter-out $(PLUGIN).bin $< $(PHONY),$^) \
 		   -T $(IMAGE_TYPE) -e $(CONFIG_SPL_TEXT_BASE)