drm/mm: Convert to drm_printer

Including all drivers. I thought about keeping small compat functions
to avoid having to change all drivers. But I really like the
drm_printer idea, so figured spreading it more widely is a good thing.

v2: Review from Chris:
- Natural argument order and better name for drm_mm_print.
- show_mm() macro in the selftest.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1483009764-8281-1-git-send-email-daniel.vetter@ffwll.ch

drivers/gpu/drm/qxl/qxl_ttm.c

@@ -463,13 +463,13 @@ static int qxl_mm_dump_table(struct seq_file *m, void *data)
 	struct drm_mm *mm = (struct drm_mm *)node->info_ent->data;
 	struct drm_device *dev = node->minor->dev;
 	struct qxl_device *rdev = dev->dev_private;
-	int ret;
 	struct ttm_bo_global *glob = rdev->mman.bdev.glob;
+	struct drm_printer p = drm_seq_file_printer(m);
 
 	spin_lock(&glob->lru_lock);
-	ret = drm_mm_dump_table(m, mm);
+	drm_mm_print(mm, &p);
 	spin_unlock(&glob->lru_lock);
-	return ret;
+	return 0;
 }
 #endif