fix accelsim: ACC_READ cannot be 0 (it's used to check if a bit is set)
fix accelsim: ACC_READ cannot be 0 (it's used to check if a bit is set)

before that, accel data was all 0, but since the gyrosim also publishes
accel data, it was not a problem.

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