board support add px4_i2c_bus_external/px4_spi_bus_external

cmake/common/px4_base.cmake

src/drivers/batt_smbus/batt_smbus.cpp

src/drivers/bmi055/bmi055.hpp

src/drivers/bmi055/bmi055_accel.cpp

src/drivers/bmi055/bmi055_gyro.cpp

src/drivers/bmi160/bmi160.cpp

src/drivers/bmi160/bmi160.hpp

src/drivers/bmm150/bmm150.cpp

src/drivers/bmm150/bmm150.hpp

src/drivers/boards/common/board_common.h

src/drivers/boards/px4fmu-v2/board_config.h

src/drivers/boards/px4fmu-v3/CMakeLists.txt

src/drivers/boards/px4fmu-v3/px4fmu_i2c.c

src/drivers/boards/px4fmu-v3/px4fmu_spi.c

src/drivers/boards/px4fmu-v4/board_config.h

src/drivers/boards/sitl/board_config.h

src/drivers/bst/bst.cpp

src/drivers/device/Device.hpp

src/drivers/device/nuttx/cdev_platform.hpp

src/drivers/device/nuttx/i2c_nuttx.cpp