util: Refactor virResctrlAllocSetID to set allocation ID
util: Refactor virResctrlAllocSetID to set allocation ID

Refactor virResctrlAllocSetID generating an error if an attempt
is made to overwrite the existing value.

Signed-off-by: Wang Huaqiang <d50c218ff14e8070a7288e1c175a5d8637d7ddbf@intel.com>
Reviewed-by: John Ferlan <87558058f6f829e5ec976c8ef960720af4ff9c7d@redhat.com>

nertpinx/libvirt,nertpinx/libvirt,andreabolognani/libvirt,nertpinx/libvirt,andreabolognani/libvirt,eskultety/libvirt,zippy2/libvirt,eskultety/libvirt,eskultety/libvirt,crobinso/libvirt,andreabolognani/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,olafhering/libvirt,olafhering/libvirt,zippy2/libvirt,jardasgit/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,libvirt/libvirt,fabianfreyer/libvirt,crobinso/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,eskultety/libvirt,nertpinx/libvirt,andreabolognani/libvirt,jfehlig/libvirt,eskultety/libvirt,jardasgit/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,crobinso/libvirt,jardasgit/libvirt,crobinso/libvirt,libvirt/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt