kinetis-based-boards: use FLASHDEPS instead of flash: xxxx.

With the canned recipe for flashing, flash dependencies should be
added to FLASHDEPS, instead of writing `flash: dependencies`. This
ensures that both flash and flash-only depend on the same prerequisites.

boards/common/frdm/Makefile.include

@@ -23,8 +23,7 @@ export OPENOCD_PRE_VERIFY_CMDS += \
   -c 'resume 0x20000000'
 export OPENOCD_EXTRA_INIT
 
-.PHONY: flash
-flash: $(RIOTCPU)/$(CPU)/dist/wdog-disable.bin
+FLASHDEPS += $(RIOTCPU)/$(CPU)/dist/wdog-disable.bin
 
 export OPENOCD_CONFIG ?= $(RIOTBOARD)/common/frdm/dist/old-openocd-$(CPU_FAMILY).cfg
 endif

boards/mulle/Makefile.include

@@ -58,8 +58,7 @@ export OPENOCD_PRE_VERIFY_CMDS += \
   -c 'resume 0x20000000'
 export PRE_FLASH_CHECK_SCRIPT = $(RIOTCPU)/$(CPU)/dist/check-fcfield-elf.sh
 
-.PHONY: flash
-flash: $(RIOTCPU)/$(CPU)/dist/wdog-disable.bin
+FLASHDEPS += $(RIOTCPU)/$(CPU)/dist/wdog-disable.bin
 
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk

boards/pba-d-01-kw2x/Makefile.include

@@ -10,8 +10,7 @@ export CPU_MODEL ?= mkw21d256vha5
 PORT_LINUX ?= /dev/ttyACM0
 PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbmodem*)))
 
-.PHONY: flash
-flash: $(RIOTCPU)/$(CPU)/dist/wdog-disable.bin
+FLASHDEPS += $(RIOTCPU)/$(CPU)/dist/wdog-disable.bin
 
 # We need special handling of the watchdog if we want to speed up the flash
 # verification by using the MCU to compute the image checksum after flashing.