qemu_firmware: only set nfeatures on success
qemu_firmware: only set nfeatures on success

The field is set just before returning on success.

Signed-off-by: Marc-André Lureau <a6f2b960a4aca61381fc650a67901b2ac8e83e6d@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Signed-off-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

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