This adds the port parameter to the stm32loader flash script. This was
necessary to allow flashing on macOS X where the default port is not
autodetected correctly and needs to be specified, e.g. by running:
BOARD=lobaro-lorabox PORT=/dev/tty.SLAB_USBtoUART \
make -C examples/lorawan flash term`
The file always exist so no need to do '-include'.
Replaced using:
sed -i 's|-\(include $(RIOTCPU)/.*/Makefile.features\)|\1|' \
$(git grep -l '$(RIOTCPU)/.*/Makefile.features' boards)
