build: use new toolchain variables for tools

This change migrates the values of `CC`, `CPP`, `AS` and other toolchain
variables to the new `$(toolchain)-$(tool)` variables, which were
introduced by the toolchain refactor patch. These variables should be
equivalent to the values that they're replacing.

Change-Id: I644fe4ce82ef1894bed129ddb4b6ab94fb04985d
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/plat/st/common/common.mk b/plat/st/common/common.mk
index 7f93961..f49112d 100644
--- a/plat/st/common/common.mk
+++ b/plat/st/common/common.mk
@@ -43,7 +43,7 @@
 STM32MP_UART_PROGRAMMER		?=	0
 STM32MP_USB_PROGRAMMER		?=	0
 
-$(eval DTC_V = $(shell $(DTC) -v | awk '{print $$NF}'))
+$(eval DTC_V = $(shell $($(ARCH)-dtc) -v | awk '{print $$NF}'))
 $(eval DTC_VERSION = $(shell printf "%d" $(shell echo ${DTC_V} | cut -d- -f1 | sed "s/\./0/g" | grep -o "[0-9]*")))
 DTC_CPPFLAGS			+=	${INCLUDES}
 DTC_FLAGS			+=	-Wno-unit_address_vs_reg
diff --git a/plat/st/common/common_rules.mk b/plat/st/common/common_rules.mk
index f39caab..7f45bf2 100644
--- a/plat/st/common/common_rules.mk
+++ b/plat/st/common/common_rules.mk
@@ -49,7 +49,7 @@
 
 ${BUILD_PLAT}/$(PLAT)-%.o: ${BUILD_PLAT}/fdts/%-bl2.dtb $(STM32_BINARY_MAPPING) bl2
 	@echo "  AS      $${PLAT}.S"
-	${Q}${AS} ${ASFLAGS} ${TF_CFLAGS} \
+	${Q}$($(ARCH)-as) -x assembler-with-cpp $(TF_CFLAGS_$(ARCH)) ${ASFLAGS} ${TF_CFLAGS} \
 		-DDTB_BIN_PATH=\"$<\" \
 		-c $(word 2,$^) -o $@
 
@@ -57,14 +57,14 @@
 
 tf-a-%.elf: $(PLAT)-%.o ${STM32_TF_LINKERFILE}
 	@echo "  LDS     $<"
-ifneq ($(findstring gcc,$(notdir $(LD))),)
-	${Q}${LD} -o $@ $(subst --,-Wl$(comma)--,${STM32_TF_ELF_LDFLAGS}) -nostartfiles -Wl,-Map=$(@:.elf=.map) -Wl,-dT ${STM32_TF_LINKERFILE} $<
+ifneq ($(findstring gcc,$(notdir $($(ARCH)-ld))),)
+	${Q}$($(ARCH)-ld) -o $@ $(subst --,-Wl$(comma)--,${STM32_TF_ELF_LDFLAGS}) -nostartfiles -Wl,-Map=$(@:.elf=.map) -Wl,-dT ${STM32_TF_LINKERFILE} $<
 else
-	${Q}${LD} -o $@ ${STM32_TF_ELF_LDFLAGS} -Map=$(@:.elf=.map) --script ${STM32_TF_LINKERFILE} $<
+	${Q}$($(ARCH)-ld) -o $@ ${STM32_TF_ELF_LDFLAGS} -Map=$(@:.elf=.map) --script ${STM32_TF_LINKERFILE} $<
 endif
 
 tf-a-%.bin: tf-a-%.elf
-	${Q}${OC} -O binary $< $@
+	${Q}$($(ARCH)-oc) -O binary $< $@
 	@echo
 	@echo "Built $@ successfully"
 	@echo
diff --git a/plat/st/stm32mp1/cert_create_tbbr.mk b/plat/st/stm32mp1/cert_create_tbbr.mk
index 5b1a3ed..e747e39 100644
--- a/plat/st/stm32mp1/cert_create_tbbr.mk
+++ b/plat/st/stm32mp1/cert_create_tbbr.mk
@@ -11,9 +11,8 @@
 PLAT_INCLUDE	+= -I${PLAT_DIR}include
 
 src/stm32mp1_tbb_cert.o: ${PLAT_DIR}stm32mp1_tbb_cert.c
-	${Q}${HOSTCC} -c ${HOSTCCFLAGS} ${INC_DIR} $< -o $@
+	${Q}$(host-cc) -c ${HOSTCCFLAGS} ${INC_DIR} $< -o $@
 
 PLAT_OBJECTS	= src/stm32mp1_tbb_cert.o
 
 OBJECTS		+= $(PLAT_OBJECTS)
-