Makefile: Fix ${FIP_NAME} to be rebuilt only when needed

Currently ${FIP_DEPS} as prerequisite for ${BUILD_PLAT}/${FIP_NAME}
contains .PHONY targets check_$(1) and therefore ${BUILD_PLAT}/${FIP_NAME}
is always rebuilt even when other file target prerequisites are not
changed.

These changes fix above issue and ${BUILD_PLAT}/${FIP_NAME} target is
rebuilt only when its prerequisites are changed.

There are 3 changes:

Content of check_$(1) target is moved into check_$(1)_cmd variable so it
can be easily reused.

.PHONY check_$(1) targets are not put into ${FIP_DEPS} and ${FWU_FIP_DEPS}
dependencies anymore and required checks which are in ${CHECK_FIP_CMD} and
${CHECK_FWU_FIP_CMD} variables are executed as part of targets
${BUILD_PLAT}/${FIP_NAME} and ${BUILD_PLAT}/${FWU_FIP_NAME} itself.

To ensure that ${BUILD_PLAT}/${FIP_NAME} and ${BUILD_PLAT}/${FWU_FIP_NAME}
are rebuilt even when additional dependency file image added by
TOOL_ADD_IMG is changed, this file image (if exists) is added as file
dependency to...

Makefile

@@ -1261,6 +1261,7 @@ certificates: ${CRT_DEPS} ${CRTTOOL}
 endif
 
 ${BUILD_PLAT}/${FIP_NAME}: ${FIP_DEPS} ${FIPTOOL}
+	$(eval ${CHECK_FIP_CMD})
 	${Q}${FIPTOOL} create ${FIP_ARGS} $@
 	${Q}${FIPTOOL} info $@
 	@${ECHO_BLANK_LINE}
@@ -1277,6 +1278,7 @@ fwu_certificates: ${FWU_CRT_DEPS} ${CRTTOOL}
 endif
 
 ${BUILD_PLAT}/${FWU_FIP_NAME}: ${FWU_FIP_DEPS} ${FIPTOOL}
+	$(eval ${CHECK_FWU_FIP_CMD})
 	${Q}${FIPTOOL} create ${FWU_FIP_ARGS} $@
 	${Q}${FIPTOOL} info $@
 	@${ECHO_BLANK_LINE}

make_helpers/build_macros.mk

@@ -214,21 +214,28 @@ define TOOL_ADD_IMG
     # This is the uppercase form of the first parameter
     $(eval _V := $(call uppercase,$(1)))
 
+    # $(check_$(1)_cmd) variable is executed in the check_$(1) target and also
+    # is put into the ${CHECK_$(3)FIP_CMD} variable which is executed by the
+    # target ${BUILD_PLAT}/${$(3)FIP_NAME}.
+    $(eval check_$(1)_cmd := \
+        $(if $(value $(_V)),,$$$$(error "Platform '${PLAT}' requires $(_V). Please set $(_V) to point to the right file")) \
+        $(if $(wildcard $(value $(_V))),,$$$$(error '$(_V)=$(value $(_V))' was specified, but '$(value $(_V))' does not exist)) \
+    )
+
     $(3)CRT_DEPS += check_$(1)
-    $(3)FIP_DEPS += check_$(1)
+    CHECK_$(3)FIP_CMD += $$(check_$(1)_cmd)
 ifeq ($(4),1)
     $(eval ENC_BIN := ${BUILD_PLAT}/$(1)_enc.bin)
     $(call ENCRYPT_FW,$(value $(_V)),$(ENC_BIN))
     $(call TOOL_ADD_IMG_PAYLOAD,$(1),$(value $(_V)),$(2),$(ENC_BIN),$(3), \
 		$(ENC_BIN))
 else
-    $(call TOOL_ADD_IMG_PAYLOAD,$(1),$(value $(_V)),$(2),,$(3))
+    $(call TOOL_ADD_IMG_PAYLOAD,$(1),$(value $(_V)),$(2),$(if $(wildcard $(value $(_V))),$(value $(_V)),FORCE),$(3))
 endif
 
 .PHONY: check_$(1)
 check_$(1):
-	$$(if $(value $(_V)),,$$(error "Platform '${PLAT}' requires $(_V). Please set $(_V) to point to the right file"))
-	$$(if $(wildcard $(value $(_V))),,$$(error '$(_V)=$(value $(_V))' was specified, but '$(value $(_V))' does not exist))
+	$(check_$(1)_cmd)
 endef
 
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