delete snapdragon_rc_pwm and passthrough config

ROMFS/px4fmu_common/init.d/20000_snapdragon_rc_pwm

ROMFS/px4fmu_common/init.d/rcS

cmake/configs/nuttx_auav-x21_default.cmake

cmake/configs/nuttx_mindpx-v2_default.cmake

cmake/configs/nuttx_nxphlite-v3_default.cmake

cmake/configs/nuttx_px4-same70xplained-v1_default.cmake

cmake/configs/nuttx_px4fmu-v2_default.cmake

cmake/configs/nuttx_px4fmu-v2_test.cmake

cmake/configs/nuttx_px4fmu-v3_default.cmake

cmake/configs/nuttx_px4fmu-v4_default.cmake

cmake/configs/nuttx_px4fmu-v4pro_default.cmake

cmake/configs/nuttx_px4fmu-v5_default.cmake

cmake/configs/nuttx_px4nucleoF767ZI-v1_default.cmake

src/drivers/snapdragon_rc_pwm/CMakeLists.txt

src/drivers/snapdragon_rc_pwm/snapdragon_rc_pwm.cpp