Fix another bin/qmk reference (#12856)

tmk_core/avr.mk

@@ -294,7 +294,7 @@ ifneq ($(strip $(BOOTLOADER)), qmk-dfu)
 	$(error Please set BOOTLOADER = qmk-dfu first!)
 endif
 	make -C lib/lufa/Bootloaders/DFU/ clean
-	bin/qmk generate-dfu-header --quiet --keyboard $(KEYBOARD) --output lib/lufa/Bootloaders/DFU/Keyboard.h
+	$(QMK_BIN) generate-dfu-header --quiet --keyboard $(KEYBOARD) --output lib/lufa/Bootloaders/DFU/Keyboard.h
 	$(eval MAX_SIZE=$(shell n=`$(CC) -E -mmcu=$(MCU) $(CFLAGS) $(OPT_DEFS) tmk_core/common/avr/bootloader_size.c 2> /dev/null | sed -ne 's/\r//;/^#/n;/^AVR_SIZE:/,$${s/^AVR_SIZE: //;p;}'` && echo $$(($$n)) || echo 0))
 	$(eval PROGRAM_SIZE_KB=$(shell n=`expr $(MAX_SIZE) / 1024` && echo $$(($$n)) || echo 0))
 	$(eval BOOT_SECTION_SIZE_KB=$(shell n=`expr  $(BOOTLOADER_SIZE) / 1024` && echo $$(($$n)) || echo 0))