Makefile: Reduce use of $^ in build rules

It's rare to use all of a target's prerequisites in a recipe - replace
most cases with $< (the target's first prerequisite).

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/atsam/Makefile

@@ -59,7 +59,7 @@ lib/bossac/bin/bossac:
 	$(Q)make -C lib/bossac bin/bossac
 
 flash: $(OUT)klipper.bin lib/bossac/bin/bossac
-	@echo "  Flashing $^ to $(FLASH_DEVICE) via bossac"
+	@echo "  Flashing $< to $(FLASH_DEVICE) via bossac"
 	$(Q)if [ -z $(FLASH_DEVICE) ]; then echo "Please specify FLASH_DEVICE"; exit 1; fi
-	$(Q)lib/bossac/bin/bossac -U -p "$(FLASH_DEVICE)" -a -e -w $(OUT)klipper.bin -v -b
+	$(Q)lib/bossac/bin/bossac -U -p "$(FLASH_DEVICE)" -a -e -w $< -v -b
 	$(Q)lib/bossac/bin/bossac -p "$(FLASH_DEVICE)" -b -R > /dev/null 2>&1 || true

src/atsamd/Makefile

@@ -61,6 +61,6 @@ BOSSAC_OFFSET-$(CONFIG_MACH_SAMD21) := 0x2000
 BOSSAC_OFFSET-$(CONFIG_MACH_SAMD51) := 0x4000
 
 flash: $(OUT)klipper.bin lib/bossac/bin/bossac
-	@echo "  Flashing $^ to $(FLASH_DEVICE) via bossac"
+	@echo "  Flashing $< to $(FLASH_DEVICE) via bossac"
 	$(Q)if [ -z $(FLASH_DEVICE) ]; then echo "Please specify FLASH_DEVICE"; exit 1; fi
-	$(Q)lib/bossac/bin/bossac -U -p "$(FLASH_DEVICE)" -a --offset=$(BOSSAC_OFFSET-y) -w $(OUT)klipper.bin -v -b -R
+	$(Q)lib/bossac/bin/bossac -U -p "$(FLASH_DEVICE)" -a --offset=$(BOSSAC_OFFSET-y) -w $< -v -b -R

src/avr/Makefile

@@ -29,6 +29,6 @@ $(OUT)klipper.elf.hex: $(OUT)klipper.elf
 	$(Q)$(OBJCOPY) -j .text -j .data -O ihex $< $@
 
 flash: $(OUT)klipper.elf.hex
-	@echo "  Flashing $^ to $(FLASH_DEVICE) via avrdude"
+	@echo "  Flashing $< to $(FLASH_DEVICE) via avrdude"
 	$(Q)if [ -z $(FLASH_DEVICE) ]; then echo "Please specify FLASH_DEVICE"; exit 1; fi
-	$(Q)avrdude -p$(CONFIG_MCU) -c$(CONFIG_AVRDUDE_PROTOCOL) -P"$(FLASH_DEVICE)" -D -U"flash:w:$(OUT)klipper.elf.hex:i"
+	$(Q)avrdude -p$(CONFIG_MCU) -c$(CONFIG_AVRDUDE_PROTOCOL) -P"$(FLASH_DEVICE)" -D -U"flash:w:$(<):i"

src/pru/Makefile

@@ -31,7 +31,7 @@ $(OUT)pru0.elf: $(patsubst %.c, $(OUT)src/%.o,$(pru0-y))
 
 $(OUT)pru1.elf: $(OUT)klipper.elf
 	@echo "  Linking $@"
-	$(Q)$(CC) $(CFLAGS_pru1.elf) $^ -o $@
+	$(Q)$(CC) $(CFLAGS_pru1.elf) $< -o $@
 
 flash: $(OUT)pru0.elf $(OUT)pru1.elf
 	@echo "  Flashing"

src/stm32f1/Makefile

@@ -47,5 +47,5 @@ $(OUT)klipper.bin: $(OUT)klipper.elf
 	$(Q)$(OBJCOPY) -O binary $< $@
 
 flash: $(OUT)klipper.bin
-	@echo "  Flashing $^ to $(FLASH_DEVICE) via stm32flash"
-	$(Q)stm32flash -w $(OUT)klipper.bin -v -g 0 $(FLASH_DEVICE)
+	@echo "  Flashing $< to $(FLASH_DEVICE) via stm32flash"
+	$(Q)stm32flash -w $< -v -g 0 $(FLASH_DEVICE)