bdi: remove enum wb_congested_state

enum wb_congested_state and the member 'congested' in bdi_writeback are
useless since commit a88f2096d5a2 ("remove congestion tracking
framework"), so remove it.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Xiu Jianfeng <[e-mail]>
Reviewed-by: Jan Kara <[e-mail]>
Cc: NeilBrown <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

include/linux/backing-dev-defs.h

···
 	WB_start_all,		/* nr_pages == 0 (all) work pending */
 };
 
-enum wb_congested_state {
-	WB_async_congested,	/* The async (write) queue is getting full */
-	WB_sync_congested,	/* The sync queue is getting full */
-};
-
 enum wb_stat_item {
 	WB_RECLAIMABLE,
 	WB_WRITEBACK,
···
 
 	atomic_t writeback_inodes;	/* number of inodes under writeback */
 	struct percpu_counter stat[NR_WB_STAT_ITEMS];
-
-	unsigned long congested;	/* WB_[a]sync_congested flags */
 
 	unsigned long bw_time_stamp;	/* last time write bw is updated */
 	unsigned long dirtied_stamp;