fix vehicle_roi.msg: re-add ROI_WPINDEX
fix vehicle_roi.msg: re-add ROI_WPINDEX

The indexes are directly mapped from MAVLink, thus the actual value is
important.

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