[media] media-entity.h: Correct KernelDoc of media_entity_enum_empty()

The function media_entity_enum_empty() returns true when the bitmap
of the input parameter media entity enumeration is empty instead of marked.
This patch corrects the return value description of the function.
Signed-off-by: Liu Ying <gnuiyl@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

include/media/media-entity.h

@@ -486,7 +486,7 @@ media_entity_enum_test_and_set(struct media_entity_enum *ent_enum,
  *
  * @ent_enum: Entity enumeration
  *
- * Returns true if the entity was marked.
+ * Returns true if the entity was empty.
  */
 static inline bool media_entity_enum_empty(struct media_entity_enum *ent_enum)
 {