drm/i915: IS_IRONLAKE is synonymous with gen == 5

So remove the redundant bit in the capabilities block and
s/IS_IRONLAKE/IS_GEN5/.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index a8f408f..0c6eb97 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -491,7 +491,7 @@
 		intel_ring_advance(dev, ring);
 	}
 
-	if (IS_G4X(dev) || IS_IRONLAKE(dev)) {
+	if (IS_G4X(dev) || IS_GEN5(dev)) {
 		intel_ring_begin(dev, ring, 2);
 		intel_ring_emit(dev, ring, MI_FLUSH |
 				MI_NO_WRITE_FLUSH |