It is now provided at cpu level

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)

    C++ requires to init struct attributes in order of there definition
    in the respective struct.

Signed-off-by: dylad <dylan.laduranty@mesotic.com>

Signed-off-by: dylad <dylan.laduranty@mesotic.com>

All boards define a default PORT_LINUX and PORT_DARWIN
arduino-atmega-common uses PORT_LINUX and PORT_DARWIN accordingly

- adapted the SPI driver
- merged SPI driver for samr21 and saml21
- adapted all boards using the CPU

No need for these, as $(RIOTBOARD)/$(BOARD)/Makefile.dep is
globally included from $(RIOBASE)/Makefile.dep.

- changed names of pad selection macros according to
  the CPU changes