drm/i915: [dinq] shut up six instances of -Warray-bounds

Introduced in commits c1cd90ed and d27b1e0e

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: s/fix/shut up in the commit msg and add a comment to the
BUG_ON.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -704,6 +704,7 @@ static void i915_ring_error_state(struct seq_file *m,
 				  struct drm_i915_error_state *error,
 				  unsigned ring)
 {
+	BUG_ON(ring > VCS); /* shut up confused gcc */
 	seq_printf(m, "%s command stream:\n", ring_str(ring));
 	seq_printf(m, "  HEAD: 0x%08x\n", error->head[ring]);
 	seq_printf(m, "  TAIL: 0x%08x\n", error->tail[ring]);