Merge pull request #5624 from OTAkeys/pr/mtdi_flash

boards/native/Makefile.dep

boards/native/board_init.c

boards/native/include/board.h

cpu/native/Makefile

cpu/native/include/mtd_native.h

cpu/native/include/native_internal.h

cpu/native/mtd/Makefile

cpu/native/mtd/mtd_native.c

cpu/native/startup.c

cpu/native/syscalls.c

drivers/include/mtd.h

drivers/mtd/Makefile

drivers/mtd/mtd-vfs.c

drivers/mtd/mtd.c

tests/unittests/tests-mtd/Makefile

tests/unittests/tests-mtd/Makefile.include

tests/unittests/tests-mtd/tests-mtd.c

tests/unittests/tests-mtd/tests-mtd.h