px4-alias.sh_in: allow for spaces in 'set' alias
px4-alias.sh_in: allow for spaces in 'set' alias

Required for expressions like:
set LOGGER_ARGS "${LOGGER_ARGS} -f"

krbeverx/Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,acfloria/Firmware,acfloria/Firmware,PX4/Firmware,acfloria/Firmware,PX4/Firmware,acfloria/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,PX4/Firmware,acfloria/Firmware,PX4/Firmware,acfloria/Firmware,krbeverx/Firmware,PX4/Firmware