stm32f469-disco: replace $HOST_DIR/usr with $HOST_DIR in flash script

Manual change because the script uses ${OUTPUT_DIR}/host instead of
${HOST_DIR}.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

board/stmicroelectronics/stm32f469-disco/flash.sh

@@ -8,7 +8,7 @@ if ! test -d "${OUTPUT_DIR}" ; then
     exit 1
 fi
 
-${OUTPUT_DIR}/host/usr/bin/openocd -f board/stm32f469discovery.cfg \
+${OUTPUT_DIR}/host/bin/openocd -f board/stm32f469discovery.cfg \
   -c "init" \
   -c "reset init" \
   -c "flash probe 0" \