schema: smbios: allow any strings
schema: smbios: allow any strings

The smbios docs allow any string to be passed and libvirt does not
really do any validation on them. Allow passing any string.

Partially resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1373535

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