Changes to get PX4 config to build. Also some warning removal

ChangeLog

arch/arm/src/common/up_mdelay.c

arch/arm/src/stm32/stm32_otgfsdev.c

arch/arm/src/stm32/stm32_rcc.h

arch/arm/src/stm32/stm32_sdio.c

configs/Kconfig

configs/README.txt

configs/nucleus2g/include/board.h

configs/px4fmu-v2_upstream/Kconfig

configs/px4fmu-v2_upstream/include/board.h

configs/px4fmu-v2_upstream/include/nsh_romfsimg.h

configs/px4fmu-v2_upstream/nsh/Make.defs

configs/px4fmu-v2_upstream/nsh/defconfig

configs/px4fmu-v2_upstream/src/Makefile

configs/px4fmu-v2_upstream/src/board_config.h

configs/px4fmu-v2_upstream/src/px4fmu2_init.c

configs/px4fmu-v2_upstream/src/px4fmu2_led.c

configs/px4fmu-v2_upstream/src/px4fmu_can.c

configs/px4fmu-v2_upstream/src/px4fmu_spi.c

configs/px4fmu-v2_upstream/src/px4fmu_usb.c