drm: Extract drm_bridge.h

We don't want to burry the bridge structures kerneldoc in drm_crtc.h.

Cc: Archit Taneja <archit.taneja@gmail.com>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160831160913.12991-3-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 4840466..0ee052b 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -23,10 +23,9 @@
 
 #include <linux/err.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 
-#include <drm/drm_crtc.h>
-
-#include "drm/drmP.h"
+#include <drm/drm_bridge.h>
 
 /**
  * DOC: overview