drm/framebuffer: Print task that allocated the fb in debug info.

This is is very useful to finding sources of leaked framebufers.
The fbcon fb is annotated with [fbcon], to give it a better name
than kworker.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171220093545.613-3-maarten.lankhorst@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

include/drm/drm_framebuffer.h

@@ -121,6 +121,12 @@ struct drm_framebuffer {
 	 * @base: base modeset object structure, contains the reference count.
 	 */
 	struct drm_mode_object base;
+
+	/**
+	 * @comm: Name of the process allocating the fb, used for fb dumping.
+	 */
+	char comm[TASK_COMM_LEN];
+
 	/**
 	 * @format: framebuffer format information
 	 */