lib: virDomainPinIOThread: Remove spurious overflow check
lib: virDomainPinIOThread: Remove spurious overflow check

Internal structures use unsigned int, so there's no need for this legacy
check that was copied from the vCPU pinning api.

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