imx: makefile: drop the use of imx8mimage.sh

After switch to use binman, no need to use the bash script
to check file exsiting or not. And there is bug that
the script will be executed everytime Makefile is used which is
confusing people.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index 63e28c6..bfff79f 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -114,8 +114,7 @@
 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 $$?; fi)
 else ifeq ($(CONFIG_ARCH_IMX8M), y)
 IMAGE_TYPE := imx8mimage
-IMX8M_DEPFILES := $(srctree)/tools/imx8m_image.sh
-DEPFILE_EXISTS := $(shell $(CPP) $(cpp_flags) -x c -o spl/u-boot-spl.cfgout $(srctree)/$(IMX_CONFIG);if [ -f spl/u-boot-spl.cfgout ]; then $(IMX8M_DEPFILES) spl/u-boot-spl.cfgout 0; echo $$?; fi)
+DEPFILE_EXISTS := 0
 else
 IMAGE_TYPE := imximage
 DEPFILE_EXISTS := 0
@@ -150,16 +149,18 @@
 
 ifdef CONFIG_ARM64
 ifeq ($(CONFIG_ARCH_IMX8M), y)
-SPL:
+
+SPL: spl/u-boot-spl.bin spl/u-boot-spl.cfgout FORCE
 
 MKIMAGEFLAGS_flash.bin = -n spl/u-boot-spl.cfgout \
 		   -T $(IMAGE_TYPE) -e $(CONFIG_SPL_TEXT_BASE)
 flash.bin: MKIMAGEOUTPUT = flash.log
 
+spl/u-boot-spl.cfgout: $(IMX_CONFIG) FORCE
+	$(Q)mkdir -p $(dir $@)
+	$(call if_changed_dep,cpp_cfg)
+
 spl/u-boot-spl-ddr.bin: spl/u-boot-spl.bin spl/u-boot-spl.cfgout FORCE
-ifeq ($(DEPFILE_EXISTS),0)
-	$(IMX8M_DEPFILES) spl/u-boot-spl.cfgout 1
-endif
 
 flash.bin: spl/u-boot-spl-ddr.bin u-boot.itb FORCE
 	$(call if_changed,mkimage)