[media] vb2: convert vb2_vmarea_handler refcount from atomic_t to refcount_t

Use refcount_t to manage the refcount to the memory type specific buffer
videobuf2 buffer implementations. refcount_t is better suitable for the
purpose than atomic_t.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/include/media/videobuf2-memops.h b/include/media/videobuf2-memops.h
index 36565c7a..a6ed091 100644
--- a/include/media/videobuf2-memops.h
+++ b/include/media/videobuf2-memops.h
@@ -16,6 +16,7 @@
 
 #include <media/videobuf2-v4l2.h>
 #include <linux/mm.h>
+#include <linux/refcount.h>
 
 /**
  * struct vb2_vmarea_handler - common vma refcount tracking handler
@@ -25,7 +26,7 @@
  * @arg:	argument for @put callback
  */
 struct vb2_vmarea_handler {
-	atomic_t		*refcount;
+	refcount_t		*refcount;
 	void			(*put)(void *arg);
 	void			*arg;
 };