drm/mode: introduce wrapper to read framebuffer refcount.

Avoids drivers knowing where the kref is stored.

[airlied: add kerneldoc]
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 644e80b..8593394 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1917,7 +1917,7 @@
                          fbdev_fb->base.depth,
                          fbdev_fb->base.bits_per_pixel,
                          fbdev_fb->base.modifier[0],
-                         atomic_read(&fbdev_fb->base.refcount.refcount));
+                         drm_framebuffer_read_refcount(&fbdev_fb->base));
                describe_obj(m, fbdev_fb->obj);
                seq_putc(m, '\n');
        }
@@ -1935,7 +1935,7 @@
 			   fb->base.depth,
 			   fb->base.bits_per_pixel,
 			   fb->base.modifier[0],
-			   atomic_read(&fb->base.refcount.refcount));
+			   drm_framebuffer_read_refcount(&fb->base));
 		describe_obj(m, fb->obj);
 		seq_putc(m, '\n');
 	}