stm32mp1: update rules for stm32image tool

In heavy parallel builds, it has sometimes been seen issues with the
tool not generated before it was needed. Change some rules order and
dependency to solve that.

Change-Id: I8f4b4f46a2ea0fe496bc66bca47c66d1c81d3c99
Signed-off-by: Yann Gautier <yann.gautier@st.com>

plat/st/stm32mp1/platform.mk

@@ -197,11 +197,13 @@ endif
 .PHONY: check_dtc_version stm32image clean_stm32image
 .SUFFIXES:
 
-all: check_dtc_version ${STM32_TF_STM32} stm32image
+all: check_dtc_version stm32image ${STM32_TF_STM32}
 
 distclean realclean clean: clean_stm32image
 
-stm32image:
+stm32image: ${STM32IMAGE}
+
+${STM32IMAGE}: ${STM32IMAGE_SRC}
 	${Q}${MAKE} CPPFLAGS="" --no-print-directory -C ${STM32IMAGEPATH}
 
 clean_stm32image:
@@ -234,10 +236,12 @@ tf-a-%.bin:		tf-a-%.elf
 			@echo "Built $@ successfully"
 			@echo
 
-tf-a-%.stm32:		tf-a-%.bin stm32image
+tf-a-%.stm32:		${STM32IMAGE} tf-a-%.bin
 			@echo
-			@echo "Generated $@"
+			@echo "Generate $@"
 			$(eval LOADADDR =  $(shell cat $(@:.stm32=.map) | grep RAM | awk '{print $$2}'))
 			$(eval ENTRY =  $(shell cat $(@:.stm32=.map) | grep "__BL2_IMAGE_START" | awk '{print $$1}'))
-			${STM32IMAGE} -s $< -d $@ -l $(LOADADDR) -e ${ENTRY} -v ${STM32_TF_VERSION}
+			${Q}${STM32IMAGE} -s $(word 2,$^) -d $@ \
+				-l $(LOADADDR) -e ${ENTRY} \
+				-v ${STM32_TF_VERSION}
 			@echo