mpu6000: added "mpu6000 testerror" command
mpu6000: added "mpu6000 testerror" command

used to generate a error case for reset testing

mje-nz/PX4-Firmware,darknight-007/Firmware,krbeverx/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,Aerotenna/Firmware,acfloria/Firmware,jlecoeur/Firmware,PX4/Firmware,jlecoeur/Firmware,PX4/Firmware,jlecoeur/Firmware,jlecoeur/Firmware,mcgill-robotics/Firmware,mje-nz/PX4-Firmware,darknight-007/Firmware,acfloria/Firmware,acfloria/Firmware,acfloria/Firmware,dagar/Firmware,Aerotenna/Firmware,PX4/Firmware,Aerotenna/Firmware,Aerotenna/Firmware,jlecoeur/Firmware,jlecoeur/Firmware,acfloria/Firmware,acfloria/Firmware,mje-nz/PX4-Firmware,mcgill-robotics/Firmware,mcgill-robotics/Firmware,jlecoeur/Firmware,krbeverx/Firmware,mcgill-robotics/Firmware,krbeverx/Firmware,PX4/Firmware,PX4/Firmware,krbeverx/Firmware,darknight-007/Firmware,mcgill-robotics/Firmware,darknight-007/Firmware,Aerotenna/Firmware,PX4/Firmware,Aerotenna/Firmware,mje-nz/PX4-Firmware,dagar/Firmware,dagar/Firmware,PX4/Firmware,mje-nz/PX4-Firmware,mcgill-robotics/Firmware,dagar/Firmware,darknight-007/Firmware,dagar/Firmware,krbeverx/Firmware,dagar/Firmware,acfloria/Firmware,Aerotenna/Firmware,mje-nz/PX4-Firmware,jlecoeur/Firmware,dagar/Firmware,mcgill-robotics/Firmware