Merge pull request #12261 from cladmi/pr/frdm/fix_flashing

boards/frdm: fix flashing from invalid state

boards/common/frdm/Makefile.include

@@ -34,5 +34,9 @@ export PRE_FLASH_CHECK_SCRIPT = $(RIOTCPU)/$(CPU)/dist/check-fcfield.sh
 # setup serial terminal
 include $(RIOTMAKE)/tools/serial.inc.mk
 
+# The board can become un-flashable after some execution,
+# use connect_assert_srst to always be able to flash or reset the board.
+export OPENOCD_RESET_USE_CONNECT_ASSERT_SRST ?= 1
+
 # this board uses openocd
 include $(RIOTMAKE)/tools/openocd.inc.mk