piofirmware:Base the debug message buffer size on the defconfig
piofirmware:Base the debug message buffer size on the defconfig

  Recover 16 bytes. Size of debug max message is 40 so limit
  the usart tx buffer to same size.

jlecoeur/Firmware,mcgill-robotics/Firmware,krbeverx/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,Aerotenna/Firmware,PX4/Firmware,Aerotenna/Firmware,acfloria/Firmware,mcgill-robotics/Firmware,mje-nz/PX4-Firmware,jlecoeur/Firmware,dagar/Firmware,dagar/Firmware,PX4/Firmware,mcgill-robotics/Firmware,dagar/Firmware,krbeverx/Firmware,mcgill-robotics/Firmware,mje-nz/PX4-Firmware,PX4/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,Aerotenna/Firmware,Aerotenna/Firmware,dagar/Firmware,krbeverx/Firmware,acfloria/Firmware,jlecoeur/Firmware,PX4/Firmware,jlecoeur/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,mje-nz/PX4-Firmware,mcgill-robotics/Firmware,mcgill-robotics/Firmware,acfloria/Firmware,Aerotenna/Firmware,PX4/Firmware,PX4/Firmware,jlecoeur/Firmware,dagar/Firmware,Aerotenna/Firmware,mcgill-robotics/Firmware,jlecoeur/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,Aerotenna/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,jlecoeur/Firmware,dagar/Firmware,acfloria/Firmware,jlecoeur/Firmware