drm/ttm: move populated state into page flags

Just use the top bit of page flags to store the populated state.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200915024007.67163-8-airlied@gmail.com

include/drm/ttm/ttm_tt.h

@@ -42,6 +42,8 @@ struct ttm_operation_ctx;
 #define TTM_PAGE_FLAG_SG              (1 << 8)
 #define TTM_PAGE_FLAG_NO_RETRY	      (1 << 9)
 
+#define TTM_PAGE_FLAG_PRIV_POPULATED  (1 << 31)
+
 enum ttm_caching_state {
 	tt_uncached,
 	tt_wc,
@@ -70,22 +72,21 @@ struct ttm_tt {
 	struct sg_table *sg; /* for SG objects via dma-buf */
 	struct file *swap_storage;
 	enum ttm_caching_state caching_state;
-	bool populated;
 };
 
 static inline bool ttm_tt_is_populated(struct ttm_tt *tt)
 {
-	return tt->populated;
+	return tt->page_flags & TTM_PAGE_FLAG_PRIV_POPULATED;
 }
 
 static inline void ttm_tt_set_unpopulated(struct ttm_tt *tt)
 {
-	tt->populated = false;
+	tt->page_flags &= ~TTM_PAGE_FLAG_PRIV_POPULATED;
 }
 
 static inline void ttm_tt_set_populated(struct ttm_tt *tt)
 {
-	tt->populated = true;
+	tt->page_flags |= TTM_PAGE_FLAG_PRIV_POPULATED;
 }
 
 /**