bridge_driver: Resolve Coverity CHECKED_RETURN warning
bridge_driver: Resolve Coverity CHECKED_RETURN warning

The networkRegister() didn't check the return status of the
virRegisterNetworkDriver() call like other callers, so just
check and handle here as well.

jardasgit/libvirt,nertpinx/libvirt,andreabolognani/libvirt,eskultety/libvirt,libvirt/libvirt,shugaoye/libvirt,datto/libvirt,agx/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt,jardasgit/libvirt,jfehlig/libvirt,zippy2/libvirt,rlaager/libvirt,elmarco/libvirt,shugaoye/libvirt,shugaoye/libvirt,jfehlig/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,olafhering/libvirt,taget/libvirt,olafhering/libvirt,nertpinx/libvirt,taget/libvirt,zippy2/libvirt,rlaager/libvirt,eskultety/libvirt,agx/libvirt,eskultety/libvirt,crobinso/libvirt,rlaager/libvirt,taget/libvirt,fabianfreyer/libvirt,crobinso/libvirt,olafhering/libvirt,taget/libvirt,zippy2/libvirt,shugaoye/libvirt,VenkatDatta/libvirt,rlaager/libvirt,agx/libvirt,andreabolognani/libvirt,datto/libvirt,elmarco/libvirt,libvirt/libvirt,andreabolognani/libvirt,olafhering/libvirt,VenkatDatta/libvirt,eskultety/libvirt,datto/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,nertpinx/libvirt,elmarco/libvirt,jardasgit/libvirt,nertpinx/libvirt,elmarco/libvirt,libvirt/libvirt,datto/libvirt,datto/libvirt,libvirt/libvirt,agx/libvirt,elmarco/libvirt,VenkatDatta/libvirt,crobinso/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,eskultety/libvirt,rlaager/libvirt,shugaoye/libvirt,taget/libvirt,agx/libvirt,crobinso/libvirt,zippy2/libvirt,andreabolognani/libvirt,VenkatDatta/libvirt