sna: Assert that the mode/ring are set when marking active bo

As we use the current ring to encode upon the bo relocs, we need that
ring to be properly setup prior to performing relocations.

References: https://bugs.freedesktop.org/show_bug.cgi?id=70461
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

src/sna/kgem.c

@@ -4880,6 +4880,7 @@ uint32_t kgem_add_reloc(struct kgem *kgem,
 	assert(index < ARRAY_SIZE(kgem->reloc));
 	kgem->reloc[index].offset = pos * sizeof(kgem->batch[0]);
 	if (bo) {
+		assert(kgem->mode != KGEM_NONE);
 		assert(bo->refcnt);
 		while (bo->proxy) {
 			DBG(("%s: adding proxy [delta=%d] for handle=%d\n",