qemu: Introduce qemuDomainDeviceDefValidateController
qemu: Introduce qemuDomainDeviceDefValidateController

Introduce the bare bones helper to validate whether the controller
definition is valid.

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