radeon: remove duplicate declaration of struct radeon_bo_manager in radeon_bo.h

Reviewed-by: Simon Ser <contact@emersion.fr>
Signed-off-by: suijingfeng <suijingfeng@loongson.cn>
diff --git a/radeon/radeon_bo.h b/radeon/radeon_bo.h
index 37478a0..6e20c6c 100644
--- a/radeon/radeon_bo.h
+++ b/radeon/radeon_bo.h
@@ -48,7 +48,6 @@
     uint32_t                    size;
 };
 
-struct radeon_bo_manager;
 
 void radeon_bo_debug(struct radeon_bo *bo, const char *op);