Make NuttX drivers cross platform (VDev -> CDev)

cmake/configs/posix_rpi_common.cmake

cmake/configs/posix_sitl_default.cmake

posix-configs/rpi/px4_fw.config

src/drivers/airspeed/airspeed.cpp

src/drivers/airspeed/airspeed.h

src/drivers/boards/rpi/board_config.h

src/drivers/boards/sim/board_config.h

src/drivers/boards/sitl/board_config.h

src/drivers/device/device.h

src/drivers/device/i2c_posix.cpp

src/drivers/device/i2c_posix.h

src/drivers/device/sim.cpp

src/drivers/device/spi.h

src/drivers/device/vdev.cpp

src/drivers/device/vdev.h

src/drivers/device/vdev_posix.cpp

src/drivers/device/vfile.cpp

src/drivers/device/vfile.h

src/drivers/iridiumsbd/IridiumSBD.cpp

src/drivers/led/led.cpp