drm/i915: add a LLC feature flag in device description

LLC is not SNB/IVB-specific, so we should check for it in a more generic
way.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -83,6 +83,7 @@ static int i915_capabilities(struct seq_file *m, void *data)
 	B(supports_tv);
 	B(has_bsd_ring);
 	B(has_blt_ring);
+	B(has_llc);
 #undef B
 
 	return 0;