AV-X board support

Jenkinsfile

ROMFS/px4fmu_common/init.d/rc.interface

ROMFS/px4fmu_common/init.d/rc.sensors

cmake/configs/nuttx_av-x-v1_default.cmake

platforms/nuttx/Images/av-x-v1.prototype

platforms/nuttx/nuttx-configs/Make.defs.in

platforms/nuttx/nuttx-configs/av-x-v1/include/board.h

platforms/nuttx/nuttx-configs/av-x-v1/include/nsh_romfsimg.h

platforms/nuttx/nuttx-configs/av-x-v1/nsh/defconfig

platforms/nuttx/nuttx-configs/av-x-v1/scripts/ld.script

src/drivers/boards/av-x-v1/CMakeLists.txt

src/drivers/boards/av-x-v1/board_config.h

src/drivers/boards/av-x-v1/init.c

src/drivers/boards/av-x-v1/sdio.c

src/drivers/boards/av-x-v1/spi.c

src/drivers/boards/av-x-v1/timer_config.c

src/drivers/px4fmu/px4fmu_params.c