ekf2 fix GPS fix_type comparison
ekf2 fix GPS fix_type comparison

 - fixes Coverity CID 306253

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