qemu: Add -mem-path even with numa
    
    So since the introduction of the memory-backend-file object until now we
    only added '-mem-path' for non-NUMA guests and we used the parameters of
    the memory-backend-file object to specify the path to the hugetlbfs
    mount.  But hugepages can be also used without memory-backend-file
    object, as it used to be before its introduction.  Let's just get this
    part of the code back and properly append the '-mem-path' for NUMA
    guests as well, but only when the memory backend is not needed.
    
    This parameter is already being applied when no numa is requested and
    because we still use memory-object-file unconditionally for
    hugepage-backed NUMA guests, this should not fire until later.
    
    Signed-off-by: Martin Kletzander <mkletzan@redhat.com>